Objective To retrospectively audit and describe maternal and foetal outcomes in pregnant women with prosthetic mechanical heart valves (MHV) using various formulations of anticoagulation, namely: (1) warfarin only versus (2) warfarin with sequential therapy with unfractionated heparin (UFH) or enoxaparin or (3) dose adjusted enoxaparin only. Design A 6-year single site retrospective audit from 2017 to 2022. Setting The study was conducted at a single site tertiary hospital, Inkosi Albert Luthuli Central Hospital in Durban, South Africa. Population All pregnant women with a history of mechanical valve replacement requiring lifelong anticoagulation. Methods A retrospective audit of all hospital records using keywords (warfarin, enoxaparin, pregnancy, mechanical heart valves) were used to identify and extract eligible participants for inclusion in the study. Main outcome measures The main outcome sought to describe maternal and foetal outcomes with a focus on maternal thrombo embolic complications, bleeding and foetal affectation in particular warfarin toxicity and fetal wastage. Results The study showed that 9% of pregnant women with MHV were at risk of thrombo embolic complications (TEC), with 9.8% in the warfarin group and 7.9% in the enoxaparin group (p= 0.69). There were higher rates of post-partum bleeding complications in the enoxaparin group (p= 0.035). In particular, individuals treated with enoxaparin had a 20% significantly higher likelihood of achieving live births compared to those treated with warfarin, (risk ratio (RR): 1.20; 95% CI: 1.06-1.07, p<0.001 Conclusion Pregnant women on therapeutic anticoagulation for mechanical heart valve prosthesis are at significant risk for adverse maternal morbidity.