Thank you to Adam Vella for inspiring this clinical question.


What’s the deal with NSAIDs in pregnancy?

Ibuprofen and naproxen are category B drugs in the 1st and 2nd trimesters. Catergory D in the 3rd. (aspirin is category D throughout pregnancy)

We know NSAIDs are bad in the last trimester. They affect the kidney and urine output, leading to oligohydramnios.  They cause premature closure of the ductus arteriosus (though fortunately this is reversible with discontinuation).

Early pregnancy is much more of a gray area. A 2012 analysis of the National Birth Defects Registry demonstrates wide spread use of NSAIDs by women in early pregnancy (some 22%), but “only mild-to-moderate” increases in prevalence of birth defects in this group. ¬†However, scary things like neural tube defects and cleft palates.

NSAIDs are also associated with higher rates of miscarriage in the 1st trimester. In a UK registry, miscarriage was associated with NSAID use around time of conception or use >1 week. In that country, NSAIDs are not contraindicated in early pregnancy, just advised “to use with caution”, ie short exposures.

Unfortunately ACOG seems to have no clinical policy on the matter. With Tylenol being catergory B in all trimesters, with more unambiguous data, it would be hard not to advocate for its use over NSAIDs.