Incidence of postpartum thrombosis and preterm delivery in women with antiphospholipid antibodies and recurrent pregnancy loss.

Objective: To determine the frequency of preterm deliveries and postpartum thrombotic events (TE) in pregnancies resulting in live birth in women with antiphospholipid antibodies (aPL) and a history of recurrent pregnancy loss (RPL) but without prior TE.

Methods: We reviewed the pregnancy outcomes of women referred to our clinic with a history of RPL. Prepregnancy investigation of RPL included history of TE and aPL positivity (anticardiolipin IgG and lupus anticoagulant). We recorded use of anticoagulation therapy during and after pregnancy, obstetric outcome, gestational age at delivery, and postpartum course. Included in our study were women with unexplained RPL with no history of TE attending our clinic who subsequently had pregnancies that resulted in a live birth.

Results: Over a 5-year period, 260 women with RPL and no history of TE had a live birth at our clinic. Eighty-seven (33.5%) were positive for aPL and 173 (66.5%) were negative for aPL. Twenty-four percent of deliveries in the aPL-positive group occurred before 37 weeks' gestation compared to 9.8% of deliveries in the aPL-negative group (p = 0.004; 95% CI 0.052-0.234). There were no antepartum TE in either group. One woman in the aPL-positive group (1.1%) had a deep vein thrombosis 3.5 weeks postpartum while receiving prophylactic anticoagulant therapy, compared to none in the aPL-negative group.

Conclusion: A significantly higher proportion of aPL-positive patients had preterm deliveries compared to aPL-negative patients, but pregnancy-related TE was infrequent: 99.0% of aPL-positive women with a history of RPL and no prior TE who had a live birth at our clinic had an uneventful pregnancy, delivery, and postpartum course.