Maternal and fetal outcomes in acute hepatic porphyria: A Swedish National Cohort Study.

Current knowledge of pregnancy and perinatal outcomes in women with acute hepatic porphyria (AHP) is largely based on biochemical disease models, case reports, and case series. We performed a nationwide, registered-based cohort study to investigate the association between maternal AHP and the risk of adverse pregnancy and perinatal outcomes. All women in the Swedish Porphyria Register with confirmed AHP aged 18 years or older between 1987 and 2015 and matched general population comparators, with at least one registered delivery in the Swedish Medical Birth Register were included. Risk ratios (RRs) of pregnancy complications, delivery mode and perinatal outcomes were estimated and adjusted for maternal age at delivery, area of residency, birth year and parity. Women with acute intermittent porphyria (AIP), the most common form of AHP, were further categorized according to maximal lifetime urinary porphobilinogen (U-PBG) levels. The study included 214 women with AHP and 2174 matched comparators. Women with AHP presented with a higher risk for pregnancy-induced hypertensive disorder (aRR 1.73, 95% CI 1.12-2.68), gestational diabetes (aRR 3.41, 95% CI 1.69-6.89), and small-for-gestational-age birth (aRR 2.08, 95% CI 1.26-3.45). In general, RRs were higher among women with AIP who had high lifetime U-PBG levels. Our study shows an increased risk for pregnancy induced hypertensive disease, gestational diabetes, and small for gestational age births for AHP women, with higher relative risks for women with biochemically active AIP. No increased risk for perinatal death or malformations was observed.