Low Molecular Weight Heparin and Pregnancy Outcomes in Women with Inherited Thrombophilia: A Systematic Review and Meta-analysis

Aim: To determine whether the use of low molecular weight heparin (LMWH) improves the pregnancy outcomes in women with inherited thrombophilia by conducting a meta-analysis of randomized controlled trials and observational studies.

Methods: A systematic literature search of several databases was conducted through September 19, 2020 to identify relevant studies. The outcomes of interest included live birth and adverse pregnancy outcomes (APOs). The overall risk estimates were pooled using random-effects meta-analysis.

Results: Ten randomized controlled trials and 12 cohort studies were included. In the meta-analyses of randomized controlled trials, the effectiveness of LMWH-treatment was found to be statistically significant in decreasing the risk of APOs (risk ratio [RR] = 0.76; 95% confidence interval [CI]: 0.61-0.95; p = 0.020), rather than in increasing the rate of live birth (RR = 1.12; 95% CI: 0.93-1.34; p = 0.230). In the meta-analyses of cohort studies, results showed that the use of LMWH was associated with a significantly higher proportion of live birth (RR = 1.86; 95% CI: 1.09-3.19; p = 0.020) as well as a significantly lower ratio of APOs (RR = 0.46; 95% CI: 0.31-0.69; p < 0.001) in women with inherited thrombophilia.

Conclusions: The use of LMWH may have a potentially beneficial effect on reducing the risk of APOs and even increasing the live birth rate in women with inherited thrombophilia. Further well-designed clinical trials with large samples are needed to address the role of LMWH in improving pregnancy outcomes among pregnant women with inherited thrombophilia.