Women with autoimmune rheumatic diseases have an elevated risk of various preterm birth (PTB) phenotypes, according to a large population-based, retrospective cohort study. Hence, the study in BJOG strongly advocates preconception counseling and close monitoring during pregnancy.
All live singleton births in California between 2007 and 2011 were analyzed, representing maternally linked hospital and birth certificate records of 2,481,516 deliveries. Patients with five prevalent autoimmune rheumatic diseases at the time of delivery were identified by ICD‐9 codes: systemic lupus erythematosus (SLE) (n = 2,272); systemic sclerosis (SSc) (n = 88); rheumatoid arthritis (RA) (n = 1,501); polymyositis/dermatomyositis (DM/PM) (n = 38); and juvenile idiopathic arthritis (JIA) (n = 187).
PTB was defined as birth between 20 weeks and less than 37 gestational weeks, based on the obstetric estimate. It was also subcategorized by gestational age: early (20 to less than 32 weeks) and late (32 to less than 37 weeks). PTB was due to either preterm premature rupture of membranes (PPROM), spontaneous, or medically indicated.
The investigators compared patients with autoimmune disease to the general obstetric population, while adjusting for maternal age, race/ethnicity, body mass index (BMI), smoking, education, payer, parity and prenatal care.
Patients with autoimmune disease had an increased relative risk (RR) for PTB for each of the five autoimmune diseases evaluated: SLE (RR 3.27; 95% confidence interval [CI]: 3.01 to 3.56); RA (RR 2.04; 95% CI: 1.79 to 2.33), SSc (RR 3.74; 95%CI: 2.51 to 5.58); JIA (RR 2.23; 95% CI: 1.54 to 3.23); and DM/PM (RR 5.26; 95%CI: 3.12 to 8.89).
“These elevated risks were observed for the majority of preterm birth phenotypes as well,” wrote the authors from Stanford University School of Medicine.
At least 90% of the women with maternal autoimmune disease started prenatal care within the first 5 months of pregnancy and were nonsmokers. In addition, 64.7% of these women were nulliparous. Furthermore, women with autoimmune diseases were more likely to be non-Hispanic White, with the exception of those with SLE.