Spontaneous preterm birth in African-American and Caucasian women receiving 17α-hydroxyprogesterone caproate.

Objective: To determine if the rates of recurrent spontaneous preterm birth in women receiving 17α-hydroxyprogesterone caproate (17P) differ according to maternal race.

Study Design: Retrospective analysis of a cohort of women enrolled in outpatient 17P administration at < 27 weeks. Maternal characteristics, obstetric history, and rates of recurrent preterm birth were determined using chi-square and multivariable Cox proportional hazards regression at two-tailed α = 0.05. Primary study outcome was defined as having a spontaneous preterm birth < 34 weeks.

Results: African-American women initiated 17P injections later (19.6 versus 18.9 weeks, p < 0.001) and discontinued injections earlier (33.2 versus 34.1 weeks, p < 0.001) than Caucasian women. Spontaneous recurrent preterm birth < 34 weeks was higher in African-Americans versus Caucasians receiving 17P (odds ratio 2.1; 95% confidence interval 1.7, 2.4). After adjusting for other significant factors, African-American race retained the strongest association with recurrent spontaneous preterm birth < 34 weeks. Within each racial group, short cervical length < 25 mm before 27 weeks' gestation had the highest hazard of recurrent spontaneous preterm delivery.

Conclusion: Despite treatment with 17P, African-American women have higher rates of recurrent preterm birth.