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

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.