Effect of laser-assisted hatching on ectopic pregnancy after frozen-thawed embryo transfer in patients with a history of ectopic pregnancy: a large cohort study

Assisted hatching (AH) influences embryo implantation, whereas ectopic pregnancy (EP) is embryo ectopic implantation and AH may influence EP. Patients with EP history are at higher risk of EP resulting from IVF/ICSI (IVF-EP), and this is associated with the number of previous EP. However, the effect of laser-AH on IVF-EP in patients with EP history has not been studied so far, so we investigated the effect and considered possible different effects in populations with different numbers of EP. This retrospective cohort study included all patients with previous EP history receiving frozen-thawed embryo transfer cycles at our center between August 2019 and August 2023. A total of 5129 cycles from 2888 patients were grouped according to AH or not. Subgroup analyses were performed based on the number of previous EP (One-EP and > = 2 EP). Binary regression analysis together with generalized estimating equation (GEE) after inverse-probability-of-treatment weighting (IPTW) were performed in all cycles, One-EP cycles, and > = 2 EP cycles respectively to clarify the effect of laser-AH. Stratified regression analysis was also performed based on embryo stage. A total of 1022 cycles were included in the AH group and 4107 cycles were included in the Non-AH group. No statistically significant difference was observed in IVF-EP rate between the two groups (1.4% vs. 2.1%, P = 0.113). In subgroup analyses, AH group had a lower IVF-EP rate than Non-AH group in the One-EP subgroup (1.0% vs. 2.2%, P = 0.028); whereas there was no statistically significant difference in the > = 2 EP subgroup (2.4% vs. 1.9%, P = 0.612). In GEE after IPTW, AH did not influence the IVF-EP rate in the entire population (aOR: 0.888, 95% CI: 0.414–1.904, P = 0.760) and One-EP population (aOR: 0.418, 95% CI: 0.154–1.131, P = 0.086), while increased risk of IVF-EP was observed of AH in > = 2 EP population (aOR: 2.438, 95% CI: 1.509–3.939, P = 0.023). Similar regression results were obtained in cleavage-embryo cycles. Laser-AH had no effect on IVF-EP after FET in patients with EP history. However, laser-AH was associated with an increased risk of IVF-EP in patients with recurrent EP, suggesting that laser-AH warrants caution in this specific population.