Influence of gestational age and reason for prior preterm birth on rates of recurrent preterm delivery.

OBJECTIVE: We sought to compare rates of recurrent spontaneous preterm birth (SPTB) in women receiving 17-α-hydroxyprogesterone caproate (17P) with prior SPTB due to preterm labor (PTL) vs preterm premature rupture of membranes (PPROM). STUDY DESIGN: Women with singleton gestation having 1 prior SPTB enrolled at 16-24.9 weeks' gestation for weekly outpatient 17P administration were identified from a database. Rates of recurrent SPTB were compared between those with prior SPTB due to PTL or PPROM overall and by gestational age at prior SPTB. RESULTS: Records from 2123 women were analyzed. The prior PTL group vs the prior PPROM group experienced higher rates of recurrent SPTB at <37 weeks (29.7% vs 22.9%, P = .004), <35 weeks (14.0% vs 9.1%, P = .004), and <32 weeks (5.9% vs 3.3%, P = .024), respectively. CONCLUSION: Reason and gestational age of prior SPTB influence the likelihood of recurrent SPTB in women receiving 17P prophylaxis.