A comprehensive meta-analysis published in BMJ Evidence-Based Medicine concludes there is no safe level of caffeine consumption for pregnant women.
Leading health authorities—including the UK NHS, American College of Obstetricians and Gynecologists, U.S. Dietary Guidelines, and European Food Safety Authority (EFSA)—recommend limiting intake to no more than 200 milligrams daily, about two cups of coffee. But research from Icelandic experts, led by Professor Jack James, indicates even low levels can harm the developing fetus.
Professor James's team reviewed 48 studies and meta-analyses from the past two decades, examining caffeine's links to miscarriage, stillbirth, low birth weight, preterm birth, and childhood acute leukemia.
Of 37 observational studies (42 outcomes), 32 showed caffeine significantly increased risks for most adverse outcomes (except preterm birth); 10 found no or inconclusive associations.
Eleven meta-analyses (17 outcomes) linked caffeine to elevated risks in 14 cases—miscarriage, stillbirth, low birth weight, and leukemia—while three showed none.
Though observational, these findings warrant further research into mechanisms. Caffeine crosses the placenta easily, and fetuses lack enzymes to metabolize it, heightening vulnerability.
Professor James cites 'substantial cumulative evidence' of harm, urging an urgent update to guidelines: Pregnant women and those planning pregnancy should avoid caffeine.
