17-alphahydroxyprogesterone caproate in women with previous spontaneous preterm delivery: does a previous term delivery affect the rate of recurrence?

OBJECTIVE: The purpose of this study was to determine the role of previous term delivery on the rate of recurrent preterm birth in women with previous spontaneous preterm delivery (SPTD) who receive 17-alphahydroxyprogesterone caproate (17P) therapy. STUDY DESIGN: Women with singleton gestations who were receiving 17P therapy were studied. Rates of recurrent SPTD were compared for 1 or >= 2 SPTD with and without a previous term delivery. RESULTS: Five thousand one hundred two women had 1 previous SPTD, and 2217 women had >= 2 SPTDs. In women with 1 previous SPTD, a previous term delivery had lower rates of SPTD at < 35 weeks (8.4% vs 11.2%; P = .002) and preterm delivery at < 32 weeks (4.7% vs 6.2%; P = .027) compared with those women with no such history. No differences were found for SPTD at < 35 weeks with >= 2 SPTDs. CONCLUSION: In patients who received 17P therapy with 1 previous SPTD, a previous term delivery confers a reduction in risk of preterm delivery at < 37, < 35, and < 32 weeks' gestation; such reduction is not evident with >= 2 previous SPTDs.