Ibuprofen in first trimester pregnancy

Ibuprofen in the first trimester is linked to several specific birth defects, but the overall risk increase is small and the evidence is observational, not conclusive.

The best available study is a 2012 case-control analysis from the National Birth Defects Prevention Study, covering about 15,000 cases and 5,500 controls across ten US states [1]. It found no large overall increase in birth defects from first-trimester NSAID use, but did find small-to-moderate associations for certain defects. For ibuprofen specifically, the odds ratios were elevated for anophthalmia or microphthalmia (about 1.9 times the background risk), some neural tube defects, oral clefts, and amniotic bands or limb body wall defects [1]. The strongest and most consistent link was with anophthalmia or microphthalmia, where aspirin and naproxen also showed elevated risks [1].

These are associations from self-reported medication use, not proof of causation. The study had several limitations: retrospective recall, potential for differential reporting between mothers of affected and unaffected infants, and multiple statistical comparisons across more than 30 defect groups, which increases the chance that some findings are due to chance [1]. The underlying reason for taking ibuprofen (fever, infection, pain) could itself contribute to birth defects, and the study could not fully separate the drug effect from the reason it was taken [1].

A small 2023 Canadian survey found that only about 5.6% of pregnant women reported using ibuprofen during pregnancy, with acetaminophen being far more common [2]. This suggests many women already avoid it, but the survey was tiny (72 women) and not designed to measure outcomes [2].

The evidence does not include a large, prospective, controlled trial comparing ibuprofen-exposed pregnancies to truly unexposed ones. That kind of study has never been done. The available data is observational and carries the usual uncertainties of that design.

My call: ibuprofen in the first trimester carries a small but measurable association with several specific birth defects, strongest for eye malformations. The absolute risk increase for any individual woman is likely small, but the evidence is too weak to call it safe. Confidence: moderate.