17-alpha hydroxyprogesterone caproate and risk for venous thromboembolism during pregnancy.

17-alpha hydroxyprogesterone caproate (17 P) is a progestin commonly used during pregnancy to reduce risk of recurrent preterm birth. History of thromboembolism is a contraindication to 17 P and the package insert for 17 P recommends discontinuation in the setting of an acute VTE event. The objective of this study was to determine whether 17 P is associated with increased risk of VTE. The MarketScan claims database was used to perform a retrospective cohort of women who underwent delivery from 4/2008 to 1/2015. We identified women who received 17 P during pregnancy based on pharmacy benefits. Risk for VTE including deep vein thrombosis, pulmonary embolism, or both was stratified based on the presence or absence of 17 P pharmacy receipt. Both antenatal and delivery hospitalization VTE events were asceratined and these periods were analyzed individually. Relative risk (RR) was determined based on 17 P receipt. Among 4,775,667 delivery hospitalizations, 18,745 women received 17 P. Among women who did not receive 17 P, 0.52% of women ( No significant increased risk for VTE was noted with 17 P receipt. While new research has led to reconsideration of clinical use of 17 P for preterm birth prevention based on efficacy, findings from this analysis do not support major risk for thrombosis.