Anticoagulant therapy for women: implications for menstruation, pregnancy, and lactation

Estrogen exposure, in the setting of pregnancy, the postpartum state, combined hormonal contraceptives (CHCs), or hormone therapy use, has been clearly associated with increased rates of venous thromboembolism (VTE). Although recurrence rates are low in these settings, up to 70% of anticoagulated menstruating individuals experience abnormal or heavy menstrual bleeding (HMB), which commonly results in iron deficiency with or without anemia. Patients taking rivaroxaban appear to experience higher rates of HMB compared with those on apixaban, dabigatran, or warfarin. HMB can often be diagnosed in a single visit with a good menstrual history assessing for factors with a known association with increased or heavy bleeding, such as changing pads or tampons more often than every 2 hours, clots larger than a quarter, and iron deficiency (ferritin <50  ng/mL). HMB can be managed with hormonal therapies, including those associated with VTE risk, such as CHCs and depot-medroxyprogesterone acetate (DMPA). In many cases, continuing CHCs or DMPA while a patient is therapeutically anticoagulated is reasonable, so long as the therapy is discontinued before anticoagulation is stopped. Modification of the anticoagulation regimen, such as decreasing to a prophylactic dose in the acute treatment period, is not currently recommended. For patients who are currently pregnant, low-molecular-weight heparin (LMWH) is still standard of care during pregnancy; routine monitoring of anti-factor Xa levels is not currently recommended. Warfarin or LMWH may be considered in the postpartum setting, but direct-acting oral anticoagulants are currently not recommended for lactating patients.