<p><strong>OBJECTIVES: </strong> The primary objective was to estimate the initiation and adherence rates of 17 α-hydroxyprogesterone caproate (17OHPC) among eligible mothers in a statewide population-based cohort of Medicaid enrollees. The secondary objectives were to (1) determine the association of maternal sociodemographic and clinical characteristics with 17OHPC utilization and (2) assess the real-world effectiveness of 17OHPC on recurrent preterm birth prevention and admission to neonatal intensive care unit (NICU).</p>

<p><strong>STUDY DESIGN: </strong> This is a retrospective cohort study using a linked, longitudinal administrative dataset of birth certificates and medical assistance claims. Medicaid-enrolled mothers in Pennsylvania were included in this study if they had at least one singleton live birth from 2014 to 2016 following at least one spontaneous preterm birth. Maternal Medicaid claims were used to ascertain the use of 17OHPC from various manufacturers, including compounded formulations. Propensity score matching was used to create a covariate balance between 17OHPC treatment and comparison groups.</p>

<p><strong>RESULTS: </strong> We identified 4,781 Medicaid-covered 17OHPC-eligible pregnancies from 2014 to 2016 in Pennsylvania, 3.4% of all Medicaid-covered singleton live births. The population-based initiation rate was 28.5% among eligible pregnancies. Among initiators, 50% received ≥16 doses as recommended, while 10% received a single dose only. The severity of previous spontaneous preterm birth was the strongest predictor for the initiation and adherence of 17OHPC. In the matched treatment ( = 1,210) and comparison groups ( = 1,210), we found no evidence of 17OHPC effectiveness. The risks of recurrent preterm birth (relative risk [RR] 1.10, 95% confidence interval [CI] 0.97-1.24) and births admitted to NICU (RR 1.00, 95% CI 0.84-1.18) were similar in treated and comparison mothers.</p>

<p><strong>CONCLUSION: </strong> The 17OHPC-eligible population represented 3.4% of singleton live births. Less than one-third of eligible mothers initiated treatment. Among initiators, 50% were treatment adherent. We found no difference in the risk of recurrent preterm birth or admission to NICU between treatment and comparison groups.</p>

<p><strong>KEY POINTS: </strong>· 3.4% of singleton live births were eligible for 17OHPC.. · About 30% of eligible mothers initiated treatment.. · We found no association of 17OHPC with recurrent preterm birth..</p>

<p>Preterm birth (PTB) is a pressing maternal and child health issue with long-standing racial inequities in outcomes and care provision. 17-Alpha-hydroxyprogesterone caproate (17OHPC) has been one of few clinical interventions for recurrent PTB prevention. Little is known about the factors influencing successful administration and receipt of 17OHPC among mothers in the Medicaid program. We conducted individual semistructured interviews with 17OHPC-eligible pregnant women and obstetric providers from two academic medical centers in Philadelphia, PA. Patient participants were publicly insured, eligible for 17OHPC treatment, and purposively sampled as either (1) actively receiving treatment or (2) declining/discontinuing treatment. Providers had experience providing care to Medicaid-enrolled patients. Interview transcripts were coded and analyzed to identify themes related to treatment acceptability, access, and adherence. Of the 17 patient participants, the mean age was 30 years. Ten providers (MDs, nurse practitioners, and registered nurses) were also interviewed. Factors facilitating 17OHPC uptake and adherence among patients included severity of prior PTB, provider counseling, and coordination among the clinic, pharmacy, and insurance. Pain was cited as the most significant barrier to 17OHPC for patients, while providers perceived social adversity and beliefs about patients' commitment to treatment to be primary patient barriers. For providers, clinical experience and practice guidelines contributed to their use of 17OHPC. Administrative complexity and coordination of services were the primary provider barrier to 17OHPC administration. Patient-provider communication is a primary driver of 17OHPC acceptability and adherence. Comprehensive patient-centered consultation may improve uptake of clinical therapies among pregnant women at high risk for PTB.</p>