Comparing pregnancy outcomes in patients with systemic lupus erythematosus (SLE) and undifferentiated connective tissue disease (UCTD): a descriptive cohort study

Background Females diagnosed with systemic lupus erythematosus (SLE) face an elevated risk of adverse pregnancy outcomes (APOs). However, the evidence regarding whether a similar association exists in patients with undifferentiated connective tissue disease (UCTD) is inconclusive. Methods We conducted a retrospective review (2006-2019) of pregnancy outcomes among patients with SLE (n = 51) and UCTD (n = 20) within our institution. We examined the occurrence of various APOs, encompassing miscarriage, stillbirth, termination, preterm birth, pre-eclampsia, eclampsia, HELLP syndrome, intrauterine growth restriction, abruption placentae, congenital heart block, or other cardiac abnormalities. Results The mean age at pregnancy was 35 ± 7.0 years for patients with SLE and 35 ± 6.8 years for those with UCTD (p = 0.349). The proportion of Caucasian women was 47% in SLE and 80% in UCTD. Pregnancies in both groups were planned (81% in SLE and 77% in UCTD), and patients presented with inactive disease at conception (96% in SLE and 89% in UCTD). Hydroxychloroquine at conception was utilized by 86% of women with SLE, in contrast to 36% in the UCTD group. Both, SLE and UCTD cohorts exhibited low rates of disease flares during pregnancy and/or puerperium (14% vs. 10%). The incidence of APOs was 15.6% in SLE patients compared to 5% in those with UCTD (Risk difference 19.5%; 95% Confidence Interval: -3.9 to 43.1; p = 0.4237). Conclusion Our study underscores the importance of strategic pregnancy planning and the maintenance of appropriate treatment throughout pregnancy to ensure optimal disease management and minimize adverse outcomes in both SLE and UCTD pregnancies.