Abstract
OBJECTIVE: To estimate the absolute and relative risk of venous thromboembolism (VTE) among women who initiate depot medroxyprogesterone acetate (DMPA) immediately postpartum compared with those who do not initiate hormonal contraception. METHODS: The IBM MarketScan Commercial Claims and Encounters databases were used to identify delivery hospitalizations among women aged 15-44 years during 2005 through 2014. Diagnosis, procedure, and drug codes were used to identify contraception, VTE, and potential confounding chronic or pregnancy-related conditions. Women who initiated DMPA during days 0 through 7 postpartum were compared with women who did not initiate hormonal contraception during days 0 through 7 postpartum. Women were followed from date of delivery through 12 weeks postpartum for the occurrence of VTE, with censoring at hormonal contraception initiation or prescription, hysterectomy, sterilization, or inpatient death. The incidence rate of VTE and 95% CIs were calculated within each group and the incidence rate ratio was calculated comparing the two groups. RESULTS: The unadjusted VTE incidence rate through 12 weeks postpartum was 0.42/10,000 women-days in the immediate postpartum DMPA group (34 events among 11,159 women contributing 805,999 days of follow-up) and 0.15/10,000 women-days in the control group (3,107 events among 3,102,011 women contributing 206,180,811 days of follow-up). The incidence rate ratio for VTE was 2.87 (95% CI 2.05-4.03) among women in the immediate postpartum DMPA group compared with women in the control group, adjusting for age alone. After adjusting for age and pregnancy-related and chronic conditions, the adjusted incidence rate ratio for VTE was 1.94 (95% CI 1.38-2.72) among women in the immediate postpartum DMPA group compared with women in the control group. CONCLUSION: Initiation of DMPA immediately postpartum is associated with a low incidence but an increased relative risk of VTE compared with nonuse of hormonal contraception.