Recurrent preterm birth in women treated with 17 α-hydroxyprogesterone caproate: the contribution of risk factors in the penultimate pregnancy

Abstract

Objective: Examine rates of recurrent, spontaneous preterm birth (PTB) in women treated prophylactically with 17 α-hydroxyprogesterone caproate (17P) when the penultimate PTB was due to preterm labor (PTL) or preterm premature rupture of the membranes (pPROM). Methods: Retrospective, descriptive, database study of 1183 singleton gestations that initiated prophylactic 17P at <21 weeks with a penultimate PTB. Primary outcomes examined were rates of recurrent PTB at <37 and <32 weeks’ gestation in the PTL (n = 939) and pPROM (n = 244) cohorts. Results: Recurrent PTB <37 weeks occurred in 38% versus 28.3% of the PTL and pPROM cohorts, respectively (p <0.005). Rates of recurrent PTB <32 weeks were similar. Logistic regression revealed three risk factors increased the odds of recurrent PTB: >1 previous PTB (OR 1.8 [95% CI: 1.33–2.44]); penultimate birth at 28–33.9 weeks’ gestation (OR 1.61 [95% CI: 1.22–2.13]); and, PTL as the indication for delivery in the penultimate PTB (OR 1.66 [95% CI: 1.16–2.37]). Conclusion: Several historical factors increase the risk for recurrent PTB in women receiving 17P. Contrary to earlier studies of PTL and pPROM recurrence, women receiving prophylactic 17P with a penultimate PTB due to pPROM are at lower risk of recurrent PTB than those with a history of PTL.