Preterm Birth Rates in a Prematurity Prevention Clinic After Adoption of Progestin Prophylaxis

Objective: To evaluate whether progestin prophylaxis influenced the odds of recurrent spontaneous preterm birth among pregnant women with a previous preterm birth.

Methods: A retrospective cohort study was performed evaluating outcomes of pregnant women with one or more previous preterm births who received prenatal care in a single academic prematurity clinic. Care algorithms were determined and revised by a single supervising physician. Progestin prophylaxis was adopted in 2004 with accelerated access to the first clinic visit adopted in 2008. Rates of preterm birth before 37, 35, and 32 weeks of gestation were compared over time.

Results: One thousand sixty-six women with a history of one or more spontaneous preterm births received care in the prematurity clinic and were delivered between January 1, 1998, and June 30, 2012. The gestational age at initiation of prenatal care declined significantly after adoption of an accelerated appointment process (median of 19.1 weeks before 2003, 16.2 weeks from 2004 to 2007, and 15.2 weeks from 2008 to 2012, P<.01), and progestin use increased from 50.8% in 2004-2007 to 80.3% after 2008 (P<.01). After adjustment for race, smoking, cerclage, and number of prior preterm deliveries, we noted a statistically significant decreased odds of spontaneous preterm birth in years 2008-2012 compared with 1998-2007 before 37 (adjusted odds ratio [OR] 0.75, 95% confidence interval [CI] 0.58-0.97) and 35 (adjusted OR 0.70, 95% CI (.52-0.94) weeks of gestation.

Conclusion: Adoption of prophylactic progestin treatment was associated with a decreased odds of recurrent preterm birth before 37 or 35 weeks of gestation after adoption of an aggressive program to facilitate early initiation of progestin treatment.

LEVEL OF EVIDENCE: II