Prenatal acetaminophen use in women with autoimmune disorders and adverse pregnancy and birth outcomes

Objectives Most women may have temporary pain for which they use analgesics, but those with autoimmune disorders have chronic pain that may be exacerbated for some during pregnancy. This study aimed to determine whether prenatal acetaminophen use was associated with an increased risk of adverse pregnancy and birth outcomes in women with autoimmune disorders. Methods Participants were enrolled between 2004 and 2018 in the MotherToBaby cohort study and limited to women with an autoimmune disorder (n = 1821). Self-reported acetaminophen use was characterized over gestation for indication, timing of use and duration. Cumulative acetaminophen use through 20 and 32 weeks was categorized into quintiles, with no acetaminophen use as the reference category. The association between acetaminophen quintile and preeclampsia or pregnancy-induced hypertension, small for gestational age and preterm birth was examined using adjusted multiple log-linear regression. Results Overall, 74% of women reported acetaminophen use during pregnancy. The most often reported indication for using acetaminophen was headache/migraines, followed by pain and injury. Risk of preeclampsia was 1.62 (95% CI: 1.10, 2.40) times greater for those in the fifth quintile of cumulative acetaminophen use through 20 weeks compared with those with no acetaminophen use. There were no associations with lower use quintiles, nor for the other outcomes. Conclusion The highest quintile of cumulative acetaminophen was associated with a modestly increased risk for preeclampsia. Some women with autoimmune conditions have pain throughout pregnancy; clinicians and patients should discuss approaches to best avoid high levels of acetaminophen in their pain management strategies.