There is no safe level of caffeine for pregnant women

Expectant and hopeful mothers should completely avoid caffeine, according to a new study published by The BMJ. The research suggests that there is no safe level of caffeine consumption prior to or during pregnancy.

Professor Jack James of Reykjavik University found more than 1,200 published studies on the link between caffeine and pregnancy outcomes. He narrowed his investigation down to focus on 48 observational studies and meta-analyses published over the past two decades.

Professor James found strong evidence of an association between maternal caffeine consumption and a range of negative pregnancy outcomes including miscarriage, stillbirth, low birth weight, childhood acute leukaemia, and childhood obesity.

Caffeine is considered the most widely consumed psychoactive substance in history, and many people drink it daily. Pregnant women are often advised that a small amount of will not harm the baby. The Dietary Guidelines for Americans and the European Food Safety Authority (EFSA) set this level at 200 milligrams of caffeine, which is roughly two cups of moderate-strength coffee per day.

Professor James reviewed the relevant articles to determine whether the recommended level of consumption for pregnant women is actually safe.

Among a total of 42 separate findings reported in 37 observational studies, 32 found that caffeine significantly increased risk of adverse pregnancy outcomes and 10 either found no link or inconclusive associations. 

There were moderate to high levels of consistency in the caffeine-related risk for miscarriage, low birth weight, childhood acute leukaemia, and stillbirth. The analyses did not find an association with preterm birth.

This is an observational study, so it does not confirm caffeine as the cause of the outcomes. Professor James noted that the results could be impacted by other confounding factors, such as maternal cigarette smoking.

However, he added that the dose-responsive nature of the associations between caffeine and adverse pregnancy outcomes, and the fact some studies found no threshold below which negative outcomes were absent, supports likely causation rather than mere association.

As a result, current health recommendations concerning caffeine consumption during pregnancy are in need of “radical revision,” said Professor James. “Specifically, the cumulative scientific evidence supports pregnant women and women contemplating pregnancy being advised to avoid caffeine.”

The study is published in the journal BMJ Evidence Based Medicine.

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By Chrissy Sexton, Earth.com Staff Writer