This chapter addresses the practical obstetric and anesthetic management of women on prophylactic heparin and therapeutic anticoagulation in the peri-partum period, and the dilemmas for obstetricians, anesthetists, and hematologists. It considers issues surrounding use of thrombolytic agents in pregnancy, and unusual but complex situations such as cardiopulmonary bypass in pregnancy. Increasing use of prophylactic anticoagulants in pregnancy, both for venous thromboprophylaxis and to modify fetal risk, as in antiphospholipid syndrome, means that more women are now reaching the peri-partum period on anticoagulants, usually a low molecular weight heparin. The safety in pregnancy of other antiplatelet agents such as clopidogrel or ticlopidine at usual therapeutic doses has not been established and they are rarely used. Most of the women requiring prophylactic doses of anticoagulant will be given one of the low molecular weight heparins (LMWH).

Successful pregnancy requires trophoblast invasion into the maternal uterine spiral arteries converting them into large dilated vessels. Microthrombi are frequently found in the vessels of the placentas from women who have experienced pregnancy loss and placental infarction has been described in the placentas of some, but not all, women who have a pregnancy loss and who have thrombophilia. Published meta-analyses suggest that factor V Leiden, prothrombin G20210A, and protein S deficiency are associated with an increased risk of recurrent early pregnancy loss and non-recurrent late pregnancy loss. Women with a history of pregnancy loss merit increased surveillance in subsequent pregnancies and should be given folic acid during pregnancy. Despite the lack of evidence from randomized, double-blind, placebo-controlled trials, many clinicians are offering women with a history of pregnancy loss found to have a heritable thrombophilia self-administered prophylactic doses of low molecular weight heparin daily low dose aspirin in subsequent pregnancies.