Caffeine is linked to miscarriage risk, new study shows

While previous research showed a link between caffeine consumption and miscarriage, this is the first study to thoroughly control for morning sickness, which typically causes many women to avoid caffeine, explained De-Kun Li, MD, Ph.D., an investigator with the Kaiser Permanente Division of Research and lead investigator of the study. “This study strengthens the association between caffeine and miscarriage risk because it removes speculation that the association was due to reduced caffeine intake by healthy pregnant women,” Li said.

To address that speculation, the study, which looked at 1,063 pregnant Kaiser Permanente members in San Francisco from October 1996 through October 1998, examined the caffeine effect among women who never changed their pattern of caffeine consumption during their pregnancy.

Women who consumed 200 mg or more of caffeine per day (two or more cups of regular coffee or five 12-ounce cans of caffeinated soda) had twice the miscarriage risk as women who consumed no caffeine, said Li. Women who consumed less than 200 mg of caffeine daily had more than 40 percent increased risk of miscarriage.

The increased risk of miscarriage appeared to be due to the caffeine itself, rather than other possible chemicals in coffee because caffeine intake from non-coffee sources such as caffeinated soda, tea and hot chocolate showed a similar increased risk of miscarriage.

“The main message for pregnant women from these findings is that they probably should consider stopping caffeine consumption during pregnancy because this research provides clearer and stronger evidence that high doses of caffeine intake during pregnancy can increase the risk of miscarriage,” said Li.


The reasons that caffeine can harm a fetus have been suspected for some time. Caffeine crosses through the placenta to the fetus, but can be difficult for the fetus to metabolize because of the under-developed metabolic system. Caffeine also may influence cell development and decrease placental blood flow, which may lead to an adverse effect on fetal development.

Women in the study were asked about their intake of caffeinated beverages as well as the type of their drinks, timing of initial drink, the frequency and amount of intake, and whether they changed consumption patterns since becoming pregnant. Sources of caffeine included coffee, tea, caffeinated soda and hot chocolate.

Researchers estimated the amount of caffeine intake in various types of beverages using the following conversion: For every 150 milliliters of beverage, 100 milligrams for caffeinated coffee, 2 milligrams for decaffeinated coffee, 39 milligrams for caffeinated tea, 15 milligrams for caffeinated soda, and 2 milligrams for hot chocolate. Information on other potential risk factors for miscarriage — including maternal age, race, education, household income marital status, smoking, alcohol consumption, hot tub use, exposure to magnetic fields during pregnancy, and symptoms related to pregnancy such as nausea and vomited — also were collected during the in-person interview and controlled during analyses. Pregnancy outcomes up to 20 weeks of gestation were determined for all participants.

Overall, 172 of women in the study (16.18 percent) miscarried. Whereas 264 women (25 percent) reported no consumption of any caffeine containing beverages during pregnancy, 635 women (60 percent) reported 0-200 mg of caffeine intake per day, and 164 women (15 percent) had 200 mg or more of daily caffeine consumption.

Critics had maintained that the association was not so much a high dose of caffeine intake that increased the risk of miscarriage, but that women with a healthy pregnancy are more likely (than those about to miscarry), to reduce their caffeine intake due to nausea, vomiting, and aversion to caffeine,” Li said. “Therefore, the critics claimed that the observed association was a result of reduction of caffeine intake by healthy pregnant women.”

So what’s a fatigued mom-to-be supposed to do for her daily energy jolt?

“If you definitely need caffeine to get you going, try keeping it to one cup or less a day. Avoiding it may be even better. Consider switching to decaffeinated coffee and other decaffeinated beverages during your pregnancy,” said Tracy Flanagan, MD, Director of Women’s Health, Kaiser Permanente Northern California. “Learn to perk up instead with natural energy boosts like a brisk walk, yoga stretches, snacking on dried fruits and nuts.”

The research appears in the current online issue of American Journal of Obstetrics and Gynecology.

Co-authors on the study included Xiaoping Weng, Ph.D. and Roxana Odouli, MSPH, also with the Kaiser Permanente Division of Research. The Study was supported in part by the California Public Health Foundation.

Mar. 23 —

MONDAY, Jan. 21 (HealthDay News) — Caffeine consumption by pregnant women can increase the risk of miscarriage, a new study reports.

And, it doesn’t matter if the caffeine comes from coffee, tea, soda or hot chocolate. What does matter is the amount — the study found that when women drink more than 200 milligrams of caffeine daily, the risk of miscarriage increases twofold.

“What we found was that if women have heavy caffeine intake — greater than 200 milligrams a day — they have double the risk of miscarriage than women that don’t have any caffeine,” said one of the study’s authors, Dr. De-Kun Li, a reproductive and perinatal epidemiologist in the division of research at Kaiser Permanente in Oakland, Calif.

Results of the study were published online in the January issue of the American Journal of Obstetrics and Gynecology.

Caffeine, the most frequently consumed drug in the world, crosses the placental barrier and reaches the developing fetus, according to the study. While previous studies have found an association between caffeine intake and miscarriage, it hadn’t been clear whether the problem was due to the caffeine or another substance in coffee, or if it had something to do with non-coffee drinkers’ lifestyles — perhaps people who didn’t drink coffee ate more fruits and vegetables, for example.

For the new study, the researchers looked at 1,063 women from the Kaiser Permanente Medical Care Program in San Francisco; they were interviewed at an average of 10 weeks’ gestation. During the study period, 16 percent of the women — 172 — had miscarriages.

The researchers found that 25 percent of the women who miscarried reported consuming no caffeine during their pregnancy. Another 60 percent said they had up to 200 milligrams of caffeine daily, and 15 percent regularly consumed more than 200 milligrams of caffeine each day.

In addition to asking about caffeine intake, the researchers also assessed the other known risk factors for miscarriage, such as smoking, a history of previous miscarriage, alcohol use and more. The researchers also compensated for nausea and vomiting during pregnancy.

“If you have a low risk of miscarriage, the effect of caffeine tends to show more,” said Li.

Li said that even among women who drank less than 200 milligrams of caffeine a day, the study found a 40 percent increased risk of miscarriage, but this finding didn’t reach the level of statistical significance.

“Women shouldn’t drink more than two regular cups of coffee a day, and hopefully they stop drinking totally for at least the first three months. It’s not a permanent stop. If they really have to drink, limit the amount to one or two cups — a regular cup is about seven and half ounces,” Li said.

But, not every doctor is convinced that there’s a direct cause-and-effect relationship between caffeine and miscarriage.

“The problem with this study is that when people miscarry, a large percentage of those miscarriages are due to genetic abnormalities, and the researchers didn’t say whether these were normal or abnormal fetuses,” said Dr. Laura Corio, an obstetrician and gynecologist at Mount Sinai Medical Center in New York City.

“Women are always worrying and wondering, ‘What did I do?’ Before we say a woman drank too much caffeine and that’s why she had a miscarriage, let’s see if it was an abnormal or normal pregnancy, said Corio.

“I think about 60 to 80 percent of miscarriages are due to genetic abnormalities,” she added.

That said, however, Corio does advise her pregnant patients to limit caffeine consumption. “Women have a responsibility to the fetus — no cigarettes, no alcohol and just one cup of coffee a day,” she said, noting that many store-bought cups of coffee contain far too much caffeine, so a woman has to be aware of how much caffeine is in her favorite coffee.

“Have less than 200 milligrams a day,” no matter what the source — coffee, tea, cola, chocolate, etcetera, Corio advised. She said caffeine has also been linked to low birth weights and smaller head circumferences.

Li also advised limiting caffeine to less than 200 milligrams a day, especially in the early months of pregnancy and in the preconception period.

More information

To learn more about caffeine and pregnancy, visit the American Pregnancy Association.

Caffeine During Pregnancy: How Much is Safe?

Consuming caffeine during pregnancy has often been debated by medical professionals concerning the risks it imposes on the developing fetus.

Caffeine is a drug and it does have real physiological effects on those that consume it and these effects are passed on to the unborn child through the placenta.

However, the question that exists is to what extent does caffeine consumed during pregnancy become harmful?

There are several hypotheses related to the possible dangers caffeine may have on the fetus. Let’s take a look at those and the research that either supports the danger or refutes it.

Caffeine During Pregnancy Causes Miscarriage

Many OBGYNs tell mothers to abstain from all caffeine during pregnancy because it increases their risk of miscarriage.

There are several studies that have shown evidence for increased risk of miscarriage or early stillbirth delivery among pregnant women who consumed more than moderate amounts of caffeine.

  • A 2002 study showed that women who drank 8 or more coffees (>800mg) were at greater risk for early stillbirth. src.
  • Another study showed that expectant mothers consuming 600mg of caffeine or more had a greater risk of miscarriage. src.
  • A California study showed that pregnant women consuming greater than 300mg of caffeine daily had a greater risk of miscarriage during the first trimester. src.
  • A 2008 study showed that those consuming 200mg of caffeine or more daily doubled their risk of miscarriage. src.
  • A 2016 study showed that both women and men who consume at least two caffeinated beverages daily in the weeks prior to conception are at greater risk for potential miscarriage. src.

Caffeine Restricts the Growth of the Fetus

There is also a belief that caffeine stunts the growth of children and unborn babies. While there isn’t evidence that it stunts the growth of children, there are some studies that support this notion for developing fetuses.

  • A 2008 study showed that pregnant women who consumed 100 mg or more of caffeine had increased risk of fetal growth restriction. src.
  • 2013 research showed that women who consumed caffeine had increased risk of delivering babies with lower birth weight. src.
  • A 2018 study of over 900 Irish mothers showed an association between caffeine intake (both coffee and tea) and adverse birth outcomes such as lower birth weight and smaller head circumference. src.

Caffeine During Pregnancy Produces Hyperactive Children

Some doctors may tell expectant mothers that caffeine during pregnancy leads to ADHD or hyperactivity disorder. However, the research conducted with this hypothesis doesn’t support this belief. Children that were exposed to caffeine in the womb were at no greater risk of developing ADHD or hyperactivity than children who weren’t. src.

Caffeine Causes Early Delivery

Some people believe that mothers who drink caffeine while pregnant will increase their chances of having a preterm delivery.

  • A 2012 Norwegian study showed no link between caffeine consumption and early preterm birth. src.
  • A 2010 American Society for Nutrition analysis of published research found no evidence that caffeine consumption leads to preterm delivery. src.

Coffee Linked to Childhood Leukemia

A recent study published in the American Journal of Obstetrics and Gynecology showed evidence of increased risk of childhood leukemia in infants whose mothers drank more than 2 cups of coffee a day.

They found that pregnant women who drank…

  1. Some coffee resulted in a 20% increased risk for their child.
  2. More than 2 cups of coffee (about 300mg of caffeine) resulted in a 60% increased risk for their child.
  3. 4 or more cups (about 600mg of caffeine) resulted in a 72% increased risk of leukemia.

It is believed that caffeine alters the fetal DNA making the baby more prone to developing leukemia.

Caffeine Linked to Possible Liver Disease in Offspring

This study wasn’t a human study but a study conducted on rats. However, the study showed that when pregnant rats were given moderate to large doses of caffeine, their babies were more likely to develop liver disease later in their life cycle.

More research is needed but the study’s authors think that expectant mothers should avoid caffeine while pregnant. The full study is published in the Journal of Endocrinology.

Caffeine, Pregnancy, and Childhood Obesity

A recent study linked caffeine consumption by pregnant mothers with an increased risk of childhood obesity.

The 15-year-long research study published in The International Journal of Obesity found that children born to mothers who did not give up their caffeine consumption during pregnancy were 89% more likely to become obese compared with children who were not exposed to caffeine in-utero.

The results were also dose-dependent, in that the more caffeine the expectant mother consumed the greater the risk of her child becoming obese.

The researchers believe this occurs because…

Brain functions have increasingly been shown to have an important role in regulating appetite and other metabolic processes. Caffeine, a neural stimulant, can alter fetal brain development impacting normal neural transmission vital to normal brain function, thus metabolic processes.

Another study conducted in Norway also found that pregnant women who consumed caffeine amounts greater than 50 mg per day had an association with a higher risk of having a child with excess growth and obesity during the first 8 years of their child’s life. This study is published in the British Medical Journal.

How Much Caffeine While Pregnant is Safe?

The American College of Obstetricians and Gynecologists says that 200mg or less a day is probably safe for the developing fetus and The World Health Organization recommends that expectant mothers consume no more than 300mg per day.

The European Food Safety Authority recently released its research regarding caffeine safety. They concluded that there isn’t enough evidence that 200 mg of caffeine or less poses any risk to the unborn child.

Also, recent research from Nationwide Children’s Hospital also found that there was no evidence that moderate caffeine consumption during pregnancy had any negative implications for the baby’s long-term cognitive and behavioral development. In the study, they analyzed the caffeine levels of blood samples taken from pregnant mothers between 1959 and 1974 and then compared the data to the children’s IQ and behavioral records.

While most of the research above does point to increased risks associated with caffeine greater than 200-300mg, there are some studies that show some risk with even lower daily amounts of caffeine.

When it comes to women consuming caffeine while pregnant, it may be wise to err on the side of caution and abstain from most or all caffeine. However, the occasional serving of dark chocolate, ice tea, or even coffee likely poses no significant risk to the health of the unborn child.

Written by Ted Kallmyer, last updated on August 2, 2019

A new study has linked caffeine with miscarriages.

People who drink more than a little caffeine when they’re trying for a pregnancy are more likely to lose that pregnancy early on, the study found. And that goes equally for men or women.

When either men or women drank three or more cups a day of caffeinated drinks before pregnancy — sodas, energy drinks or coffee — the woman was nearly twice as likely to lose that pregnancy early on. And if women consumed more caffeine after they conceived, they were also more likely to miscarry.

It’s one of the most detailed studies yet to look at something that has been noted for a while now — that high caffeine intake seems to be linked with pregnancy loss.

And it’s one of the first to show that what men eat or drink can affect fertility.

“Our findings also indicate that the male partner matters, too.”

“There’s something about drinking caffeinated beverages that is associated with pregnancy loss,” said Germaine Buck Louis of the National Institute of Child Health and Human Development, who led the study.

But women who took multivitamins before they got pregnant and early in pregnancy were 50 percent less likely to miscarry, the study found.

CDC warning to women about alcohol stirs outrage

Feb. 5, 201602:05

Their findings come out of an intensive study of 344 couples in Texas and Michigan who have agreed to be watched as they try to conceive. They wrote down every caffeinated drink they had, every serving of fish, every alcoholic drink, were weighed regularly, gave urine, blood, saliva and semen samples and the women took regular pregnancy tests.

The idea: to see what might affect a woman’s ability to get pregnant and stay pregnant.

There will be answers later to questions about mercury from fish and chemicals such as pesticides. This study looks at caffeine.

Related: Study Finds Evidence Coffee Can be a Life-Saver

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“Our findings provide useful information for couples who are planning a pregnancy and who would like to minimize their risk for early pregnancy loss,” Louis said.

Of the 344 pregnancies, 28 percent of them ended in miscarriage: 98 in total, the team reports int he journal Fertility and Sterility.

Women who were over 35 had twice the risk of an early miscarriage as younger women – that’s long been known.

But drinking three or more caffeinated beverages a day raised the risk of early pregnancy loss by 74 percent. That held whether it was before conception or afterwards.

“Our findings also indicate that the male partner matters, too,” Louis said. “Male preconception consumption of caffeinated beverages was just as strongly associated with pregnancy loss as females’.”

The study did not look for differences among various caffeinated drinks, but lumped coffee and tea together with sodas and energy drinks.

Dr. Zev Williams of the Albert Einstein College of Medicine and a spokesman for the American College of Obstetricians and Gynecologists said an important point to note is that a little caffeine is okay.

“So many studies, including this one, show that one to two cups of caffeine is not harmful,” Williams said.

“And what I do end up seeing not infrequently, an effort to really be as thorough as possible, a lot of women will go cold turkey on caffeine. And what ends up happening is invariably these women will then develop rebound headaches and take medications to treat the headaches. Those medications may be harmful,” added Williams, who was not involved int he study.

“So, it’s probably better to just have one to two cups of coffee a day and avoid to having those medications to treat a rebound caffeine withdrawal headache than to go completely cold turkey. “

“We think this is really good news. We know that vitamins protect against a lot of other adverse pregnancy outcomes.”

Louis said there has been a debate about whether caffeine causes miscarriages, or whether women who instinctively stop drinking caffeine early in pregnancy have a healthier pregnancy to start with. Because her study looked at caffeine consumption right before pregnancy, before a woman could develop an aversion to the stuff, it supports the idea that it’s the caffeine itself causing the miscarriage, Louis said.

The good news is that taking a multivitamin really helps.

‘We were really surprised at how strong the reduction in risk was,” Louis said.

“We think this is really good news. We know that vitamins protect against a lot of other adverse pregnancy outcomes.”

The Centers for Disease Control and Prevention recommends that women planning to become pregnant take folic acid, a type of B vitamin, and avoid alcohol and tobacco smoke. Not all multivitamins are safe and most doctors recommend a specially formulated prenatal vitamin.

Dr. Rebecca Starck, who chairs the gynecology department at the Cleveland Clinic, said the study cannot show cause and effect.

“Anybody of childbearing age who is contemplating pregnancy should maintain a healthy diet.”

“The main message of the study is that it’s important to seek preconception counseling,” said Starck, who was not involved in the research.

“Anybody of childbearing age who is contemplating pregnancy should maintain a healthy diet and healthy lifestyle and someone who is going to conceive should be aware of effects of lifestyle on the offspring.”

Starck noted that miscarriage is common and the study confirmed that: 25 percent to 30 percent of pregnancies end in miscarriage.

The study did not ask people what else they ate or drank besides alcohol and caffeinated beverages. Louis says it will be important to ask people about decaffeinated sodas, for instance. She said the study cannot answer questions about whether people who eat healthier diets — with more fruits and vegetables and less salt and fat — are better able to conceive and keep a pregnancy.

As with all medical and scientific studies, each one builds on the other, and it will take larger studies to answer some of the questions.

Caffeine link to miscarriage

Drinking coffee can double the risk of miscarriage reported The Guardian and many other news sources yesterday. “Pregnant women who consumed two or more mugs of coffee a day were twice as likely to miscarry than those who abstained from caffeine,” The Guardian said. The media coverage suggested that pregnant women may wish to reduce or stop drinking drinks containing caffeine, including coffee and tea.

The newspaper story is based on a study in 1,063 pregnant women in San Francisco. The study found that women who drank more than 200mg or more of caffeine a day – the amount contained in two or more regular cups of coffee or five 12oz (330 ml) cans of caffeinated drink – doubled their risk of miscarriage compared with women who drank no caffeine. However, this study has some limitations, including difficulty in making sure that the results are not affected by other factors that are known to increase the risk of a miscarriage.

Overall, the advice that pregnant women should avoid drinking too many drinks containing high levels of caffeine while they are pregnant seems sensible. Currently in the UK, the Food Standards Agency recommends that women limit their caffeine intake during pregnancy to 300mg a day.

Where did the story come from?

Dr De-Kun Li and colleagues from the Division of Research of Kaiser Permanente (a US not-for-profit integrated health care organisation) carried out this research. The study was partly funded by the California Public Health Foundation. It was published in the peer-reviewed: American Journal of Obstetrics and Gynecology.

What kind of scientific study was this?

This was a prospective cohort study looking at caffeine consumption during pregnancy and risk of miscarriage in women. All women from the San Francisco and south San Francisco areas who were members of the Kaiser Permanente Medical Care Program (KPMCP) and had a positive pregnancy test between October 1996 and October 1998 were asked to participate in the study. Of the 2,729 women researchers asked, 1,063 agreed (39%) and they completed the enrolment interview before their 15th week of pregnancy.

The enrolment interview was carried out in person, and the women were asked about what caffeine-containing beverages they had drunk since their last period. This included coffee and tea (either caffeinated or decaffeinated), caffeinated fizzy drinks and hot chocolate. They were asked how often they drank these drinks (either in a day or a week), how much they drank, at what point in the day they drank them, and if they had changed their consumption of caffeine since becoming pregnant. Some women had already miscarried by the time of their enrolment interview, and they were only asked about caffeine consumption up to the end of their pregnancy.

The researchers used the women’s answers to calculate their average daily caffeine intake. For every 150ml of liquid, caffeinated coffee was estimated to have about 100mg of caffeine, decaffeinated coffee 2mg of caffeine, 39mg for caffeinated tea, 15mg for a caffeinated fizzy drink, and 2mg for hot chocolate. The interviewers also asked the women other questions about themselves and other factors that might affect risk of miscarriage including their age, race, income, marital status, smoking, alcohol consumption, Jacuzzi use, exposure to magnetic fields in pregnancy, whether they had experienced nausea and vomiting associated with their pregnancy, and whether they had had a previous miscarriage.

The researchers followed women up to the 20th week of their pregnancy, to find out whether they had a miscarriage. They did this by searching the KPMCP in-patient and out-patient databases, looking at the women’s medical records, and by contacting the women themselves if records could not confirm their pregnancy status. The researchers then looked at whether women’s risk of miscarriage before 20 weeks varied with their caffeine intake (categorised as no caffeine a day, less than 200mg a day, or 200 mg or more a day). They also took into account the other factors that might affect miscarriage risk.

What were the results of the study?

Most women drank beverages containing up to 200mg of caffeine a day during their pregnancy. Women who drank more caffeine were more likely to have certain risk factors for miscarriage, including being older than 35, not having experienced pregnancy-related vomiting, having drunk alcohol since their last period, having used a Jacuzzi during pregnancy, and having had a previous miscarriage.

By 20 weeks, 172 of the 1,063 women (16%) had miscarried. Consuming 200mg or more of caffeine a day more than doubled the risk of miscarriage compared with drinking no caffeine, from 12 to 25 per cent. Although drinking lower amounts, up to 200mg of caffeine a day, did increase the risk of miscarriage compared with drinking no caffeine, this increase did not reach statistical significance.

What interpretations did the researchers draw from these results?

The researchers concluded that high levels of caffeine consumption in pregnancy did increase the risk of miscarriage.

What does the NHS Knowledge Service make of this study?

Although this study does have some strong points, such as its relatively large size and the fact that it attempted to follow women prospectively, it does have some limitations:

  • Only about four in 10 pregnant women who were asked, agreed to participate in the study. This may mean that the women studied were not representative of the population of the San Francisco and south San Francisco areas as a whole. The study only looked at women in a relatively small geographical area, and this may not be representative of women from different countries or of different ethnic backgrounds (for example, there was a low proportion of black women in this study – only about seven per cent).
  • Although the study tried to collect its data prospectively, some women had had a miscarriage before they were interviewed about their caffeine consumption. The fact that these women had experienced a miscarriage may have affected their reporting of their caffeine intake (either making them over- or underestimate), particularly if they thought it might have played a role in their miscarriage. It is unclear what proportion of women had experienced a miscarriage before their interview. However, the authors reported that they conducted their analyses separately according to whether women had experienced miscarriage before the interview, and found similar results.
  • The measure of the amount of caffeine drunk is also likely to have some level of error. Women were also asked to remember how much caffeine they had drunk since their last period. This may have been difficult to remember accurately, particularly in terms of exact volumes. Amounts of caffeine in drinks such as coffee will also vary with the type of coffee used and the method of preparation.
  • One of the main difficulties with interpreting this type of study is that because groups are not randomised, they are not likely to be balanced for factors that might affect outcome. This was the case in this study, where the authors report that women who drank the greatest amounts of caffeine were also more likely to have risk factors for miscarriage, including being older, having had miscarriages before, and having consumed alcohol. Although the researchers did try to account for these factors in their analyses, it is difficult to ensure that the adjustments they made would eliminate their effect. Other, unknown, factors may also be imbalanced between the groups and could be affecting the outcome.

It seems like the old saying “everything in moderation” applies here. If women are worried about their caffeine intake, it might be a good idea to moderate it for the duration of their pregnancy.

Sir Muir Gray adds…

Another bit of information that women who are pregnant should take on board, but it is always useful to see the findings of other research studies.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

Two coffees a day doubles risk of miscarriage, says US study.

The Guardian, 21 January 2008

Drinking coffee ‘can double miscarriage risk’.

The Daily Telegraph, 21 January 2008

Just two cups of coffee per day could double risk of miscarriage.

The Times, 21 January 2008

Coffee ‘doubles’ the risk of miscarriage.

Daily Mail, 21 January 2008

Coffee raises miscarriage risk – study.

Channel 4 News, 21 January 2008

Coffee ‘raises miscarriage risk’.

BBC News, 21 January 2008

Can a Couple’s Pre-Pregnancy Caffeine Lead to Miscarriage?

If you’re a woman who is considering having a baby, you may already know some of the steps to prepare your body for pregnancy, such as quitting smoking, avoiding drugs and alcohol, and taking folic acid. These steps can increase your chances of having a healthy baby.

But did you know that you should also limit your caffeine intake in food and beverages, even before you become pregnant? What’s perhaps even more surprising is that your partner should limit his caffeine intake as well.

NIH Study on Caffeine

A study by the National Institutes of Health and Ohio State University, Columbus, found that a woman has a higher risk of miscarrying if she and her partner drink beverages with more than 200 mg of caffeine per day in the weeks before conception.

In addition, women also are more likely to miscarry if they drink more than 200 mg of caffeinated beverages a day during the first seven weeks of pregnancy. Because women may not be aware that they are pregnant in those early weeks, it’s important to reduce caffeine once you’ve decided you would like to get pregnant.

A study by the National Institutes of Health and Ohio State University, Columbus, found that a woman has a higher risk of miscarrying if she and her partner drink beverages with more than 200 mg of caffeine per day in the weeks before conception.

The Many Forms of Caffeine

When you consider sources of caffeine, keep in mind there’s more to count than just coffee. Teas, sodas (both colas and some non-colas), pain relievers, energy drinks and even “energized” foods can contain caffeine. Some of these products contain as much caffeine as a cup of coffee.

The American College of Obstetricians and Gynecologists offers the following guide for the amount of caffeine found in typical beverages and foods:

Average Milligrams of Caffeine in Food and Beverages

Multivitamins Can Help Reduce Risk

The NIH study did provide some good news: Women who took a daily multivitamin before becoming pregnant had a 55 percent reduction in the risk of miscarriage. Those who took the vitamins during early pregnancy saw a risk reduction of 79 percent. Taking Vitamin B6 and folic acid also can reduce the risk of miscarriage. Folic acid also is recommended before and during pregnancy to reduce the risk of a child being born with a neural tube defect.

Bottom line—if you and your partner are planning to start or expand your family, the caffeine that both of you take can affect the health of your baby.

Couples’ pre-pregnancy caffeine consumption linked to miscarriage risk

News Release

Thursday, March 24, 2016

NIH study finds daily multivitamin before and after conception greatly reduces miscarriage risk.

A woman is more likely to miscarry if she and her partner drink more than two caffeinated beverages a day during the weeks leading up to conception, according to a new study from researchers at the National Institutes of Health and Ohio State University, Columbus. Similarly, women who drank more than two daily caffeinated beverages during the first seven weeks of pregnancy were also more likely to miscarry.

“Our findings provide useful information for couples who are planning a pregnancy and who would like to minimize their risk for early pregnancy loss”

—Germaine Buck Louis, Ph.D., Director, Division of Intramural Population Health Research

However, women who took a daily multivitamin before conception and through early pregnancy were less likely to miscarry than women who did not. The study was published online in Fertility and Sterility.

“Our findings provide useful information for couples who are planning a pregnancy and who would like to minimize their risk for early pregnancy loss,” said the study’s first author, Germaine Buck Louis, Ph.D., director of the Division of Intramural Population Health Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development.

The researchers analyzed data from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study, which was established to examine the relationship between fertility, lifestyle and exposure to environmental chemicals. The LIFE Study enrolled 501 couples from four counties in Michigan and 12 counties in Texas, from 2005 to 2009.

For the current study, researchers compared such lifestyle factors as cigarette use, caffeinated beverage consumption and multivitamin use among 344 couples with a singleton pregnancy from the weeks before they conceived through the seventh week of pregnancy.

The researchers reported their results using a statistical concept known as a hazard ratio, which estimates the chances of a particular health outcome occurring during the study time frame. For example, the researchers evaluated caffeinated beverage consumption in terms of the daily likelihood of pregnancy loss over a given time period. A score greater than 1 indicates an increased risk for pregnancy loss each day following conception, and a score less than 1 indicates a reduced daily risk.

Of the 344 pregnancies, 98 ended in miscarriage, or 28 percent. For the preconception period, miscarriage was associated with female age of 35 or above, for a hazard ratio of 1.96 (nearly twice the miscarriage risk of younger women). The study was not designed to conclusively prove cause and effect. The study authors cited possible explanations for the higher risk, including advanced age of sperm and egg in older couples or cumulative exposure to substances in the environment, which could be expected to increase as people age.

Both male and female consumption of more than two caffeinated beverages a day also was associated with an increased hazard ratio: 1.74 for females and 1.73 for males. Earlier studies, the authors noted, have documented increased pregnancy loss associated with caffeine consumption in early pregnancy. However, those studies could not rule out whether caffeine consumption contributed to pregnancy loss or was a sign of an unhealthy pregnancy. It’s possible, the authors wrote, that these earlier findings could have been the result of a healthy pregnancy, rather than caffeine consumption interfering with pregnancy. For example, the increase in food aversions and vomiting associated with a healthy pregnancy led the women to give up caffeinated beverages.

Because their study found caffeine consumption before pregnancy was associated with a higher risk of miscarriage, it’s more likely that caffeinated beverage consumption during this time directly contributes to pregnancy loss.

“Our findings also indicate that the male partner matters, too,” Dr. Buck Louis said. “Male preconception consumption of caffeinated beverages was just as strongly associated with pregnancy loss as females’.”

Finally, the researchers saw a reduction in miscarriage risk for women who took a daily multivitamin. During the preconception period, researchers found a hazard ratio of 0.45 — a 55-percent reduction in risk for pregnancy loss. Women who continued to take the vitamins through early pregnancy had a hazard ratio of 0.21, or a risk reduction of 79 percent. The authors cited other studies that found that vitamin B6 and folic acid — included in preconception and pregnancy vitamin formulations — can reduce miscarriage risk. Folic acid supplements are recommended for women of childbearing age, as their use in the weeks leading up to and following conception reduces the risk for having a child with a neural tube defect.

The U.S. Centers for Disease Control and Prevention offer information on the steps men and women of reproductive age can take to help ensure they have a healthy baby — whether they are planning pregnancy or not.

About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute’s website at

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Caffeine in pregnancy

What is caffeine?

Caffeine is a drug found in things like coffee, tea, soda, chocolate and some energy drinks and medicines. It’s a stimulant, which means it can keep you awake.

How does caffeine affect you and your baby during pregnancy?

Caffeine slightly increases your blood pressure and heart rate and the amount of urine your body makes. Caffeine may cause you to feel jittery, have indigestion or have trouble sleeping. During pregnancy, you may be especially sensitive to caffeine because it may take you longer to clear it from your body than if you weren’t pregnant.

When you have caffeine during pregnancy, it passes through the placenta to your baby. The placenta grows in your uterus (womb) and supplies the baby with food and oxygen through the umbilical cord.

You may have heard that too much caffeine can cause miscarriage (when a baby dies in the womb before 20 weeks of pregnancy). Some studies say this is true, and others don’t. Until we know more about how caffeine can affect pregnancy, it’s best to limit the amount you get to 200 milligrams each day. This is about the amount in 1½ 8-ounce cups of coffee or one 12-ounce cup of coffee. Be sure to check the size of your cup to know how much caffeine you’re getting.

What foods and drinks contain caffeine?

Caffeine is found in:

  • Coffee and coffee-flavored products, like yogurt and ice cream
  • Tea
  • Some soft drinks
  • Energy drinks
  • Chocolate and chocolate products, like chocolate syrup and hot cocoa

The amount of caffeine in foods and drinks varies a lot. For coffee and tea, the amount of caffeine depends on:

  • The brand
  • How it’s prepared
  • The type of beans or leaves used
  • The way it’s served (for example, as espresso or latte)
  • The size of the cup. Not all coffee cups are the same size, even though you think of them as a cup. Check to see how many ounces your cup has, especially if you’re buying a cup of coffee or tea. If you’re making coffee or tea at home, measure to check the size of the cup.

Some energy drinks contain large amounts of caffeine. For example, a 24-ounce energy drink may have up to 500 milligrams of caffeine. Energy drinks may have a lot of sugar, too, and they may contain ingredients that may be harmful to your baby during pregnancy. Because we don’t know a lot about all the ingredients in energy drinks, it’s best not to have them when you’re pregnant.

The amount of caffeine you get from food and drinks throughout the day adds up. So if you have a cup of coffee in the morning, you may want to limit or give up having other food and drinks during the day that have caffeine.

The list below shows the amount of caffeine in common food and drinks. The caffeine amounts are averages, so they may change depending on the brand or how the food or drink is made. Check the package label on food and drinks to know how much caffeine they contain.

What medicines contain caffeine?

Some medicines used for pain relief, migraine headaches, colds and to help keep you awake contain caffeine. The Food and Drug Administration (also called FDA) requires that labels on medicine list the amount of caffeine in the medicine.

If you’re pregnant, talk to your health care provider before taking any medicine that contains caffeine. This includes prescription and over-the-counter medicine. A prescription is an order for medicine given by a health care provider. You can buy over-the-counter medicine, like pain relievers and cold medicine, without a prescription.

Some herbal products contain caffeine. These include guarana, yerba mate, kola nut and green tea extract. Herbal products are made from herbs, which are plants that are used in cooking and for medicine. The FDA does not require that herbal products have a label saying how much caffeine they contain. If you’re pregnant, don’t use herbal products because we don’t know how much caffeine they contain.

Is caffeine safe during breastfeeding?

The American Academy of Pediatrics (AAP) says it’s safe for breastfeeding moms to have caffeine. A small amount of caffeine does get into breast milk, so limit caffeine if you’re breastfeeding. Breastfed babies of women who drink more than 2 to 3 cups of coffee a day may become fussy or have trouble sleeping.

Last reviewed: October, 2015

Mar 30, 2016 1:00 AM

Author: Libby Mitchell

Cut down on coffee and caffeinated soda if you are trying to conceive. That is the message of a new study from the National Institutes of Health that finds a woman is more likely to miscarry if she—or her partner—drank two or more caffeinated beverages prior to conception. And the study found women who drank more than two caffeinated drinks a day during the first seven weeks of pregnancy also were at a high risk of miscarriage.

“The impacts of caffeine on pregnancy have been suspected for some time,” says Joseph Stanford, MD, an OB/GYN with University of Utah Health. “This study was a better look at the question, because it had both women and men assess caffeine intake, vitamin intake, and other factors every day while they were trying to conceive. Most prior studies have asked just women about these factors after the fact.”

While the study shows a strong link between caffeine and miscarriage, it does not explain why. There are several possible explanations. “Caffeine might affect blood flow to the developing embryo in the uterus, or have a direct effect on the embryo,” says Stanford. “Prior to conception, it could impact the final maturation stages of egg or sperm development.”

The study also doesn’t examine if the caffeine is impacting the woman more prior to conception or right after conception. “It may not be completely possible to separate the impact of caffeine intake in women before conception versus very early pregnancy, since these are closely correlated,” says Stanford. “So we don’t know which time window in women has the highest impact. However, one of the most interesting things about this study is good evidence that there is impact of high caffeine intake for miscarriage in both women and men.”

The study is not all bad news, though. While the researchers found caffeine consumption increased miscarriage risk, they also found a decrease in risk among women who took multivitamins, which has been previously documented. “This is probably due to the folic acid in the vitamins,” says Stanford. “Folic acid is known as a key nutrient for rapidly dividing cells. Cells are multiplying rapidly in the early embryo.”

Much more needs to be studied when it comes to understanding pregnancy and miscarriage—especially as couples are conceiving later in life. This study points out that at any age it is important to consider lifestyle choices when it comes to trying to conceive. “When you are planning a pregnancy, it is important to be the healthiest you can be,” says Stanford.

While an energy drink has been connected with a case of “spontaneous abortion,” according to some news reports, experts say whether caffeine can trigger miscarriage is still uncertain.

About 90 incident reports linking the energy drink 5-Hour Energy with injuries or health conditions have been filed with the Food and Drug Administration over the last three years, including one case of miscarriage, the New York Times reported Thursday (Nov. 15). However, the reports do not say whether the energy drink actually caused any of these conditions.

For years, researchers have investigated whether caffeine might pose a miscarriage risk, but study results have been mixed.

Most evidence suggests that consuming less than about 300 milligrams of caffeine, or about three cups of coffee daily, does not increase the risk of miscarriage, said Dr. Mark Klebanoff, a perinatal researcher at the Research Institute at Nationwide Children’s Hospital in Columbus, Ohio.

“Keeping yourself to 300 mg a day is a good precaution” for pregnant women, Klebanoff said. (5-Hour Energy is not recommended for use by pregnant women.)

However, the effects of consuming extremely large amounts of caffeine in a short period of time has not been researched, and needs more studies, said Elizabeth Triche, a pediatric epidemiologist at Brown University’s Alpert Medical School. This type of consumption would be possible with a few shots of 5-Hour Energy — while the bottles do not list the amount of caffeine the product contains, Consumer Reports testing found the shots to contain 215 mg of caffeine each.

Uncertain link

Although some studies have found a link between caffeine consumption and an increased risk of miscarriage, these studies cannot prove that caffeine causes miscarriages.

Pregnant women commonly experience aversions to certain foods during pregnancy, and many coffee drinkers report losing their taste for coffee during pregnancy, Klebanoff said. So it could be that this aversion is a marker of a healthy pregnancy, Klebanoff said. In other words, women who continue to drink coffee might be at increased risk for miscarriage for reasons other than the caffeine consumption itself, he said.

In addition, in many studies that linked miscarriage to caffeine consumption, researchers interviewed women after their miscarriage. But the event could have affected how clearly women remember their coffee consumption, Klebanoff said. Those who have had miscarriages might put more effort into trying to remember what happened during their pregnancy than those who did not have miscarriages.

Risk of energy drinks

It’s known that caffeine can cross the placenta, but it’s unclear how the chemical might increase the risk of miscarriage, Klebanoff said.

Some studies on animals have found that extremely high doses of caffeine are teratogenic — they can cause mutations in the DNA of a fetus, leading to miscarriage, Triche said. It’s not clear what level of caffeine, if any, would cause this effect on humans, Triche said.

Having a miscarriage after drinking an energy drink would not be enough to implicate the drink as the culprit.

“These energy drinks are pretty commonly consumed, and miscarriage is a common event,” Klebanoff said. “Without knowing more of the details, it would be tough to know if it did or didn’t have anything to do with the miscarriage.”

Pass it on: Consuming less than 300 mg of caffeine a day does not appear to increase the risk of miscarriage.

Follow Rachael Rettner on Twitter @RachaelRettner, or MyHealthNewsDaily @MyHealth_MHND. We’re also on Facebook & Google+.

Here’s What Does—and Doesn’t—Cause Miscarriage

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About 15-20% of known pregnancies end in miscarriage, according to the American College of Obstetricians and Gynecologists (ACOG). But it might be reassuring to know that by the time you see a heartbeat on an ultrasound—usually by week six or seven—your chance of having a miscarriage drops to less than 5 percent, regardless of your age, says Michael Lu, M.D., associate professor of obstetrics and gynecology at the University of California, Los Angeles.

Despite how common miscarriages are, many women are surprisingly in the dark about what actually triggers them, according to research from Ohio State University College of Medicine. “Much misinformation is shared among women or passed down from older generations,” says Jonathan Schaffir, M.D., an assistant professor of obstetrics and gynecology at Ohio State University College of Medicine, who authored the study.

  • RELATED: Your Chances of Miscarriage During Pregnancy

Here’s what you need to know about what does—and doesn’t—cause miscarriage.

What Actually Causes Miscarriages

Up to 70 percent of first trimester miscarriages and 20 percent of second trimester miscarriages occur because of a glitch in the fetus’s genes, according to the March of Dimes. “When the chromosomes of the egg and those of the sperm fuse to form an embryo, they usually pair up correctly,” says Henry Lerner, M.D., an OB-GYN at Newton-Wellesley Hospital in Newton, Massachusetts. “But sometimes they get scrambled; if they’re paired incorrectly, the embryo stops developing.” It doesn’t mean that anything’s wrong with the mother or father. Plus, you’re unlikely to repeat a chromosomal error the next time you conceive, so don’t assume the past predicts your future.

Another cause of miscarriage is certain illnesses, especially those that restrict blood flow to the uterus like diabetes, thyroid disease, lupus, and heart disease, as well as others like uterine infections. Hormonal imbalance and excess caffeine intake may also play a role. Indeed, women who consumed 200 milligrams or more of caffeine each day (about two cups of regular coffee or five 12-ounce cans of caffeinated soda) had twice the miscarriage risk as those who didn’t have any, according to a study by Kaiser Permanente in the American Journal of Obstetrics and Gynecology.

  • RELATED: What Causes Miscarriage to Happen?

Finally, excess drug and alcohol use can lead to miscarriage. “Exposing a fetus to large amounts of these chemicals on a regular basis that can cause miscarriage, because they have a poisonous effect on all those developing cells,” says Dr. Schaffir.

What Doesn’t Cause Miscarriage: Debunking Common Myths

We asked Dr. Schaffir to debunk some major misconceptions about miscarriages. “It’s important for women to understand that these are just old wives’ tales—and not only are they not true, but in some cases, believing them can affect your health and wellbeing,” he says.

Can Exercise Cause Miscarriage?

Exercising or picking up a (reasonably) heavy object—a grocery bag, a toddler, or the like—are extremely unlikely to cause a miscarriage. In fact, most experts agree that exercise during pregnancy, with your doctor’s approval, can lower miscarriage risk and make mom and baby healthier. That’s because exercise reduces stress, relieves aches and pains, lowers your gestational diabetes risk, and even builds up stamina for labor.

  • RELATED: Is It Safe to Exercise During Pregnancy?

Can Stress Cause Miscarriage?

While some studies on stress and miscarriage are conflicting, Dr. Schaffir says that everyday tension or anxiety—tight deadlines at work or worrying about what labor will be like—has not been linked to pregnancy loss. What’s more, no studies have ever linked excessive bad moods to miscarriage, says Dr. Schaffir.

Things get murky when dealing with major stress, though. “We’re talking big things, like the death of a spouse or parent,” he explains, and even then, the link is not well established. Plus, women under extreme stress are also more likely to smoke, drink, or do drugs, which can affect miscarriage.

  • RELATED: How to Prevent Miscarriage: Is There Anything You Can Do?

Can Food Cause Miscarriage?

Pregnant women should maintain a healthy and nutritious diet throughout pregnancy. While foods themselves don’t cause miscarriage, certain items increase the risk for food-borne illnesses like listeria. Severe cases of listeria have been linked to miscarriage and pregnancy complications. You should avoid, for example, raw meat and fish, soft cheese, unpasteurized cheese, and deli meat; check out this article for more information.

Can Sex Cause Miscarriage?

Experts have deduced that there is no link between miscarriage and sex—even though intercourse might sometimes feel uncomfortable due to your changing body. So feel free to get intimate with your partner while expecting!

  • RELATED: Can Sex Cause a Miscarriage?

Could Miscarriage Be Mom’s Fault?

The vast majority of miscarriages occur because of chance chromosomal or genetic abnormalities in the unborn baby or, less commonly, hormonal imbalances or problems with the uterus or placenta, says Dr. Schaffir. These factors are nothing that a mom-to-be has control over. “It’s natural for a woman experiencing loss to try to explain it in some way, even if that means blaming herself,” he says. “But all women need to know that most of the time, a miscarriage is completely random, and odds are you will get pregnant after trying again.”

  • By Lauren Gelman

Why does caffeine cause miscarriage?

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