Correlation between Antinuclear Antibodies and Pregnancy Prognosis in Women with Unexplained Recurrent Pregnancy Loss

Introduction: Recurrent pregnancy loss (RPL), defined as two or more pregnancy losses, affects 1%–2% of women of reproductive age. Approximately 50% of cases remain unexplained recurrent pregnancy loss (uRPL). Antinuclear antibodies (ANAs) are detected in about 22% of women with uRPL, but whether ANA status predicts subsequent pregnancy outcomes is unclear. Aims: This study aimed to investigate the correlation between pre-pregnancy ANA positivity and subsequent pregnancy outcomes in women with uRPL. Methods: In this prospective cohort study, 386 women with uRPL underwent pre-pregnancy ANA screening via magnetic chemiluminescence immunoassay. Participants were followed for 2 years, with documentation of conception methods, any immunomodulatory treatments received, and pregnancy outcomes. Results: Of the 386 participants, 77 (20.0%) were ANA-positive and 309 were ANA-negative. During follow-up, 300 women in the ANA-negative group and 64 in the ANA-positive group achieved a pregnancy. No significant differences were observed in pregnancy outcomes (early pregnancy loss or live birth) between the ANA-positive and ANA-negative groups, nor when ANA-positive women were stratified by titre level (low vs. high). Conclusions: Pre-pregnancy ANA positivity was not associated with an increased risk of early pregnancy loss in women with uRPL, regardless of the titre cut-off used. A history of prior live birth emerged as a significant protective factor. Future research should focus on the dynamics of ANA levels during pregnancy and their prognostic implications.