Pregnancy with Mixed Connective Tissue Disease: exploration of factors influencing live birth outcomes

Abstract Background Mixed connective tissue disease (MCTD) predominantly affects women in their reproductive age (30–40 years). This study is aimed to analyze a case series of MCTD-complicated pregnancies. Methods The study design utilized a combined case-series and case-control approach. Pregnant women with MCTD were included and categorized into two groups: the live-birth group and the non-live birth group (encompassing miscarriages < 12 weeks and stillbirths ≥ 12 weeks). Primary outcomes included delivery outcomes and factors associated with live births. Results A total of 57 pregnancies from 34 mothers (median age: 33.0 years) were included. Regarding delivery outcomes, the rates for live birth, miscarriage, and stillbirth were 64.9%, 29.8%, and 5.3%, respectively. Additionally, the rates of preterm delivery, fetal growth restriction (FGR), and small-for-gestational-age (SGA) were 18.9%, 18.9%, and 27.0%, correspondingly. Regarding factors associated with live births, the live birth group demonstrated a higher prevalence and lower steroid dose usage compared to the non-live birth group (62.2% vs. 30.0%, p = 0.02; median dose: 7 mg vs. 10 mg, p = 0.03). Conclusions MCTD during pregnancy was associated with increased risks of miscarriage, stillbirth, preterm delivery, FGR, and SGA. Notably, low-dose steroid therapy has been identified as a contributing factor to successful live births.