Adherence Rates and Outcomes for 17-Hydroxyprogesterone Caproate Use in Women with a Previous History of Preterm Birth

Abstract: Background Progesterone has been utilized for preventing preterm birth with mixed results. The American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine recommended the use of 17-hydroxyprogesterone caproate (17OHPC) for risk reduction of recurrent spontaneous preterm birth (sPTB) based on the results of a multicenter randomized trial in the United States. However, recent literature lacks consensus for efficacy in the American population. Additionally, partial adherence and outcomes thereof are underreported. Hence, the relationship between 17OHPC practical adherence and outcomes were evaluated. Objective The objective of this study was to evaluate adherence, defined as receipt of >80% of intended injections, to 17OHPC, at an outpatient maternal fetal medicine center and its effect on maternal and neonatal outcomes. Materials and Methods This retrospective cohort study included women >18 years old with a singleton gestation, history of sPTB who initiated 17OHPC weekly injections between 16‒20 weeks gestational age (GA) and delivered between 2014‒2017. Women receiving 17OHPC injections outside of clinic were excluded. The primary outcome of adherence and secondary outcomes of gestational age at delivery, birthweight and neonatal outcomes were analyzed by descriptive data, independent t-test, Mann Whitney U, Chi-square test, and Fisher's Exact test where appropriate with a p-value Results Adherence to 17OHPC occurred in 38 (41.3%) of the 92 women included in the study. At baseline, there was a difference in age between groups of adherent and non-adherent women (adherent: 30.8 years, non-adherent: 27.4 years; p=0.002). The rate of sPTB less than 37 weeks, 35 weeks and 32 weeks were not significantly different in those who were adherent versus nonadherent to 17OHPC. There were no differences in GA at delivery (adherent: 36.8 ± 2.6 weeks, non-adherent: 36.5 ± 3.8 weeks; p=0.66), birth weight (adherent: 2776 grams, non-adherent: 2709 grams; p=0.68), or composite neonatal morbidity (adherent: 18.4%, non-adherent: 20.4%; p=0.86) between the adherent and non-adherent groups. Neonatal intensive care unit length of stay was 15.5 days in the adherent group compared to 15 days in the non-adherent group (p=0.72). Conclusion Real-world adherence to 17OHPC is suboptimal with less than half of women adherent to in-clinic administration. Adherence to 17OHPC was not associated with a difference in GA at delivery or birth weight compared to non-adherence. Further studies are needed to assess the outpatient administration and benefit of 17OHPC therapy.