A study found there's no safe amount of coffee for pregnant women, conflicting with national health guidelines

• Researchers say pregnant women should avoid all caffeine after they reviewed 48 existing studies on caffeine consumption and pregnancy.
• The researchers said any amount of caffeine can increase a pregnant woman's risk of miscarriage, stillbirth, and low birth weight. They found an association, not a direct link, between caffeine and pregnancy risk.
• Existing health recommendations say women can consume less than 200 mg of caffeine, or two cups of coffee, every day and still have a safe pregnancy.

Pregnant women should avoid coffee, soda, and other caffeine-containing products for the safest pregnancy possible, according to a review of 48 existing studies published in the journal BMJ Evidence-Based Medicine.

Caffeine can cause a person's heart rate and blood pressure to spike, Insider previously reported, two conditions that can negatively impact a fetus during pregnancy.

For the review, researchers from Reykjavik University in Iceland looked at data from 37 observational studies that were published after 2000, plus 11 articles that reviewed previous studies on caffeine and pregnancy. Those 11 article were published after 1998.

After reviewing the existing findings, they determined any level of caffeine consumption can increase a pregnant woman's risk of miscarriage, stillbirth, and low birth weight.

These findings go against the official existing recommendations in the UK, US, and the European Commission, which all say pregnant women can consume a moderate amount of caffeine, about the equivalent of two cups of coffee, and still be safe.

The researchers said existing guidelines need "radical revision" in light of their findings.

The study found caffeine consumption could increase the risk of miscarriage, stillbirth, and low birth-weight

After examining studies on caffeine consumption and miscarriage, nine in total, the researchers found that eight of those studies showed "significant associations," but not a direct link, between the amount of caffeine a pregnant woman consumed and her risk of experiencing a miscarriage.

One of those studies concluded caffeine-consuming pregnant women could be one-third more likely to experience miscarriage than those who don't consume any caffeine.

When it came to stillbirth, or losing a pregnancy after 2o weeks, four of the five studies the researchers examined found caffeine could increase stillbirth risk up to five times if a woman consumed a high level of caffeine.

Of the 10 low birth-weight and caffeine studies the researchers looked at, seven found a caffeine consumption increased low birth-weight risk.

The study had limitations

The review's authors didn't look at any randomized controlled trials (the "gold standard" of scientific research), so their conclusions could be flawed.

They relied on observational studies, which can lead to skewed results if a study participant misreports information, or if lifestyle factors like smoking and diet also played a role in a pregnant women's birth outcomes.

Most doctors say a moderate amount of caffeine is safe

Existing recommendations from various countries' health organizations say women can safely consume a moderate amount of caffeine during pregnancy.

The American College of Obstetrics and Gynecology suggests consuming less than 200 mg, which is equal to two cups of coffee, daily if you're pregnant. NHS, the UK's national healthcare organization, has the same recommendation.

And the World Health Organization (WHO), a global organization that offers health recommendations for countries in Europe, Southeast Asia, and Africa, says pregnant women who typically have 300 mg of caffeine daily should lower their intake.

"When it comes to the baby, their metabolism is not yet as sophisticated as an adult's, so it is harder for them to metabolize the caffeine, which means that their sleep pattern could be disrupted and they could become restless," Dr. Isis Amer-Wahlin, obstetrics and gynecology consultant for midwife app Bonzun, previously told Insider.

Caffeine can come from sources other than coffee, like chocolate, soft drinks, and medications, health experts say pregnant women should be cognizant of what they eat and drink.

"When looked at together, the evidence doesn't suggest that caffeine should be eliminated entirely, but instead, that it should be limited to a moderate amount," Amer-Wahlin said. "If you are worried or feel that you would like further clarification on the subject, make sure to speak to your doctor."

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