Background/Purpose:

Systemic autoimmune diseases expose patients to chronic inflammation, immune dysregulation, and vascular abnormalities; complications that can impact obstetric outcomes. The goal of this study was to investigate preterm birth (PTB) phenotypes in women with a variety of autoimmune diseases in large population-based data.

Methods:

Maternally linked hospital and birth certificate records for all live singleton births in California between 2007 and 2011 were analyzed (n=2,481,516) using data provided by the California Office of Statewide Health Planning and

Development (OSHPD). Prevalent autoimmune disease at delivery was identified by ICD-9 codes for Systemic Lupus Erythematosus (SLE), Discoid Lupus Erythematosus (DLE), Systemic Sclerosis (SSc), Rheumatoid Arthritis (RA), Polymyositis/Dermatomyositis (DM/PM), and Juvenile Idiopathic Arthritis (JIA).  Patients with more than one of these diagnoses were classified as “overlap”. PTB was assessed overall (20-36 weeks) and partitioned into phenotypes including pre-term premature rupture of membranes (PPROM), spontaneous, and medically induced PTB. Adjusted multivariable Poisson regression models estimated risk ratios (RR) and corresponding 95% confidence intervals for the above PTB outcomes (relative to term deliveries) for each autoimmune disease compared to the general obstetric population adjusting for maternal age, race/ethnicity, body mass index, smoking, education, payer, parity, and prenatal care.

Results:

There were 4,458 births to 4,156 distinct mothers with autoimmune diseases (SLE n=2,419, RA n=1,649, SSc n=106, DLE n=114, JIA n=198, DM/PM n=43, Overlap n=164). Greater than 90% of women in all groups initiated prenatal care in the first five months of pregnancy and were nonsmokers.  Compared to the general population, patients with systemic autoimmune diseases were more likely to deliver prematurely (Table). This increased risk persisted for all disease groups for spontaneous PTB and the majority of disease groups for both PPROM and medically indicated PTB at 32-36 weeks of gestation, with the exception of DLE.

Conclusion:

These results indicate that women with systemic autoimmune diseases have an elevated risk of preterm delivery, both spontaneous and medically indicated. Therefore, preconception counseling and close monitoring during pregnancy is important. Despite the differences in these autoimmune conditions, the risks were consistently elevated for PTB outcomes, which may provide insight into the underlying mechanism of these obstetric complications.