Maternal and neonatal outcomes among pregnant women with inflammatory myopathies

Pregnancy outcomes in women with inflammatory myopathies (IM) are not well studied. The purpose of this study is to evaluate the effects of IM on maternal and neonatal outcomes.

We conducted a retrospective cohort study using data from the Healthcare Cost and Utilization Project - Nationwide Inpatient Sample (HCUP-NIS) from 1999 to 2015. Among all pregnant women who delivered during this period, those with a diagnosis of IM were identified using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) coding, which included all patients with dermatomyositis and polymyositis. Maternal and neonatal outcomes were compared in pregnant women with and without IM. Multivariate logistic regression analysis was used to estimate the adjusted effects of IM on these outcomes.

A total of 13,792,544 pregnant women delivered between 1999 and 2015, of which 308 had a diagnosis of IM, for an overall prevalence of 2 per 100,000 pregnant women, with rates increasing over the study period. Pregnant women with IM were more likely to be older, African American and suffer from other autoimmune connective tissue diseases. IM in pregnancy was associated with greater risk of preeclampsia, caesarean delivery, major postpartum infections, urinary tract infections and longer hospital stay. Neonates born to mothers with IM had greater risk of prematurity, small for gestational age and intrauterine fetal demise.

Pregnant women with IM are at higher risk of adverse maternal and neonatal outcomes and should be closely followed in specialized centers with collaboration between maternal-fetal medicine and rheumatology.