Pregnancy outcomes in non-thrombophilic women undergoing assisted reproductive technology receiving low molecular...

Low molecular weight heparin (LMWH) has demonstrated anti-thrombotic effects and improved pregnancy outcomes in women with thrombotic disorders undergoing assisted reproductive technology (ART). However, its efficacy in non-thrombophilic populations remains unclear. This study aimed to evaluate whether LMWH administration influence pregnancy outcomes in non-thrombophilic women undergoing ART.

This retrospective cohort study included 3067 women from Tongji Hospital (2019), categorized into LMWH (n = 119) and non-LMWH (n = 2948) groups. Live birth rate (LBR) was the primary outcome, with clinical pregnancy rate (CPR), miscarriage rate (MR), multiple pregnancy rate (MPR), biochemical pregnancy rate (BPR), and ectopic pregnancy rate (EPR) as secondary outcomes. Propensity score methods and multivariable logistic regression were used to control for confounders.

Before adjustment, the LMWH group exhibited higher MPR (8.4% vs. 3.1%, P < 0.001) and MR (15.1% vs. 6.2%, P < 0.001) while other outcomes were comparable. After adjusting for confounders via multivariable logistic regression, Propensity Score Adjustment, and Inverse Probability of Treatment Weighting using propensity score (IPTW), LMWH administration was associated with significantly increased CPR (AOR = 1.54, 95% CI: 1.05-2.27; P = 0.027) and MR (AOR = 2.59, 95% CI: 1.52-4.43; P < 0.001), but not LBR, MPR, BPR. Subgroup analyses indicated improved CPR in women aged ≤ 35 years, BMI ≤ 24, and without recurrent pregnancy loss (RPL) history.

LMWH does not significantly improve the LBR in non-thrombophilic women undergoing ART. Although there may be an improvement in the CPR, this is accompanied by a concerning of observation of increased MR. These findings suggest that LMWH does not confer any significant net benefit on pregnancy outcomes in non-thrombophilic women, and its use in this population should therefore be approached with greater caution.