3B-04 - Utilization Patterns of Anticoagulants Before, During, and After Pregnancy in the United States

Background: Pregnancy induces a hypercoagulable state, requiring anticoagulant use for prophylaxis or treatment in patients at high risk for thrombosis. Heparins are considered safe during pregnancy and breastfeeding, whereas warfarin is teratogenic but safe during breastfeeding. Limited data exist on direct oral anticoagulants (DOACs) in pregnancy and on the anticoagulant treatment patterns post-DOAC introduction.

Objectives: To describe the anticoagulant utilization patterns before, during, and after pregnancy, stratified by drug class and pre-/post-DOAC market entry (2011).

Methods: Using US claims data (Medicaid 2000-18; MarketScan 2003-20), we identified live birth pregnancies with continuous enrollment from 180 days pre-last menstrual period (LMP) to 180 days after the date of delivery (DoD). Anticoagulant use (unfractionated heparins [UFH], low molecular weight heparins [LMWH], warfarin, or DOACs) was defined as >=1 prescription fill. The proportion of pregnancies with specific anticoagulant use was estimated pre-/post-DOAC introduction across pregnancy windows: pre-LMP, trimesters, and postpartum periods (0-6 weeks, 6 weeks-3 months, 3-6 months).

Results: Among 2,869,643 pregnancies in Medicaid and 1,846,669 in MarketScan, anticoagulant use was 0.3% and 0.5% pre-pregnancy, 0.5% and 1.5% during pregnancy, and 0.7% and 1.1% postpartum. Post-DOAC introduction, warfarin use declined, LMWH increased slightly, and UFH remained stable. In Medicaid post-DOAC introduction, among anticoagulant users before pregnancy, 49.0% used LMWH, 32.8% UFH, 25.0% used warfarin, and 8.5% used DOACs. LMWH dominated during pregnancy (>78.3% until 36 weeks) but dropped to 42.4% between 36 weeks and delivery. Postpartum, LMWH use was high in the first 6 weeks (79.6%) and gradually decreased to 36.7% by 3-6 months after DoD. UFH use remained stable during early pregnancy (~15%) but rose to 62.6% between 36 weeks and delivery. Postpartum, UFH use was low in the first 6 weeks (10.7%) but rose to 24.0% by 3-6 months after delivery. Warfarin use declined during pregnancy (7.8% in 1st trimester) but increased postpartum, rising from 17.0% at 6 weeks to 33.2% by 3-6 months. DOAC use was low during pregnancy (2.9% in the first trimester) and increased postpartum, from 5.1% at 6 weeks to 15.8% by 3-6 months. Observed patterns were similar in MarketScan.

Conclusions: Since the introduction of DOACs, the use of warfarin among pregnant individuals declined. However, there are still patients exposed to warfarin and DOACs during the 1st trimester and DOACs postpartum, which requires further research to evaluate outcomes among fetuses and infants.