Most previous treatment guidelines for pregnant women with mechanical heart valves (MHVs) recommended that low molecular weight heparin (LMWH) should be applied once every 12 hours and only as required to reach peak anti-Xa levels of around 1.0–1.2 IU/mL,but it is commonly associated with and subtherapeutic trough levels consequently with an inadequate level of anticoagulation. Our case report here together with a literature review suggests that dose-adjusted (Target trough anti-Xa levels of 0.6-0.7 IU/mL and with peak anti-Xa levels of around 1.0–1.2 IU/mL or less than 1.5 IU/mL) LMWH should be given thrice daily throughout pregnancy.In addition, the findings of this rare case indicate that a combination of LMWH and warfarin is effective in the treatment of small thromboses in pregnancy.