Share on Pinterest
Researchers say even small amounts of caffeine can result in a higher risk of negative health outcomes in infants. Getty Images
  • In a new study, researchers say guidelines for caffeine consumption for pregnant women need to be revised.
  • They state that any amount of caffeine consumed during pregnancy can increase the risk of low birth rate, miscarriage, and stillbirth.
  • Experts note that the study is observational and despite the increases, the risk for these pregnancy outcomes is still low overall.

Pregnant women might want to avoid drinking even a single daily cup of coffee, tea, or caffeinated soda, a new analysis of existing research suggests.

The review looked at more than 1,000 existing studies pared down to 48 observational studies and meta-analyses published over the past 20 years.

From it, researchers concluded that any caffeine consumption was associated with an increased risk of negative pregnancy outcomes, including miscarriage, stillbirth, low birth weight, and childhood acute leukemia.

Within this analysis of studies, prior research showed risks of miscarriage from caffeine consumption increasing 7 to 14 percent for each increment of 100 milligrams (mg) of caffeine consumed.

The risks of stillbirth were estimated to increase 9 to 19 percent per 100 mg of caffeine consumed.

The risk of low birth weight was calculated at increasing 10 percent per 100 mg caffeine consumed.

The average cup of coffee has around 95 mg of caffeine.

The studies analyzed also indicated a 43 percent or higher risk of childhood leukemia in children born to mothers who consumed a high amount of caffeine during pregnancy.

It also listed increased risks of the disease at any level of consumption.

“Current advice is not consistent with the level of threat indicated by biological plausibility of harm and extensive empirical evidence of actual harm,” wrote Jack E. James, PhD, the study’s lead author and a professor of psychology at Reykjavik University in Iceland. “Accordingly, current health recommendations concerning caffeine consumption during pregnancy are in need of radical revision. Specifically, the cumulative scientific evidence supports pregnant women and women contemplating pregnancy being advised to avoid caffeine.”

For example, current recommendations from the American College of Obstetricians and Gynecologists (ACOG) and other groups state that consuming less than 200 mg per day of caffeine is not associated with an increased risk of miscarriage or preterm birth.

However, researchers say their recent analysis indicates that assumption might not be true.

This latest study adds to a longstanding body of research on the link between caffeine consumption and potential negative outcomes during pregnancy.

Therefore, it’s important to understand the limitations of this analysis and how to use the information in determining one’s own risk assessments.

One consideration is that increased risks are always relative to the relative overall risks.

For instance, the childhood leukemia rate is 4.7 per 100,000, so even a large increased risk — 43 percent or higher — is still a relatively small risk in the grand scheme of things.

Another is that this analysis consists of studies that are observational in nature, which makes determining direct cause and effect difficult.

“While the study is in itself interesting, the author is correct in that it is an observational study. Observational studies are unable to control and/or account for other factors which may cause similar findings as caffeine,” Dr. G. Thomas Ruiz, the OB-GYN lead at MemorialCare Orange Coast Medical Center in Fountain Valley, California, told Healthline.

That’s one limitation, but one that study author James anticipated.

“Likely causation is supported by a compelling body of evidence, both theoretical (ie, biological plausibility) and empirical, including a strong consensus among observational studies and particularly meta-analyses, dose-response relationships, and reported absence of threshold effects,” he wrote.

“It is generally accepted that chronic exposure to chemicals during pregnancy is cause for concern,” the study says. “When the chemical of interest is caffeine, a near-universally consumed habit-forming substance of no nutritional value, the need for caution is compelling.”

Dr. Sherry A. Ross, an OB-GYN and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California, agreed.

“Despite being an observational study, there is concerning evidence that we need to treat caffeine similar to the way we treat alcohol during pregnancy,” she told Healthline. “No amount is considered safe.”