Association between laser-assisted hatching and subsequent blastocyst development in fresh day 3 cleavage-stage embryos: a retrospective cohort study using propensity score matching, generalized estimating equations, and time-sensitivity analyses
In brief
Laser-assisted hatching raises transferable blastocyst rate by up to 7% in day-3 embryos
In a propensity-matched cohort of 999 IVF cycles, laser-assisted hatching increased the proportion of embryos that reached a transferable blastocyst stage by about 5% to 7% in analyses covering 12- to 24-month windows, without improving high-quality blastocyst formation. The benefit disappeared after adjusting for calendar time, so the finding is hypothesis-generating and awaits confirmation in randomized trials.
- Journal
- Frontiers in endocrinology (Q1)
- Published
- 8 July 2026
- Study design
- Prospective / inception cohort
- Evidence level
- Level 2, Moderate (CEBM 2b)
- Authors
- Lixia Miao, Lian Zou, Min Wang, Meiling Weng, Yun Zhang, Xin Jin, et al.
- PMID
- 42488011
- DOI
- 10.3389/fendo.2026.1871377
Why clinicians should know about it
- Picked for Embryology (top studies of the week, 26 July 2026): Laser-assisted hatching improves blastocyst formation rates
Abstract
BACKGROUND: To investigate the association between laser-assisted hatching (LAH) and blastocyst developmental outcomes of day 3 (D3) cleavage-stage embryos in fresh IVF cycles, using Propensity Score Matching (PSM), Generalized Estimating Equation (GEE) analysis, and Time-sensitivity analyses. METHODS: The clinical data of 4365 couples who received in vitro fertilization (IVF) treatment at Wuxi Maternal and Child Health Hospital from January 2018 to December 2023 were retrospectively analyzed. The patients were divided into the LAH (n=3193) and the non-LAH (n=1172). To control potential confounding factors, the baseline characteristics of the two groups were balanced by 1:1 Propensity Score Matching (PSM), and 999 couples were included in each group. The Generalized Estimating Equation (GEE) was further applied to correct the multi-factor interference and evaluate the independent effect of LAH on blastocyst development. In this study, the research cohort was restricted within ±6-month, ± 12-month, and ±24-month time windows, and time-sensitivity analyses were performed to assess potential time-related confounding bias. RESULTS: After propensity score matching, LAH was associated with a higher transferable blastocyst formation rate, especially in grade II-IV embryos (P < 0.001). GEE analysis confirmed this association, whereas no significant improvement in high-quality blastocyst formation was observed. Sensitivity analyses using ±6-, ± 12-, and ±24-month windows showed no significant difference in overall blastocyst formation. For transferable blastocyst formation, no association was found in the ±6-month model, while positive associations were observed in the ±12-month model (adjusted rate difference: 4.62%, 95% CI: 1.30%-7.95%, P = 0.006) and ±24-month model (6.69%, 95% CI: 4.46%-8.92%, P < 0.001). However, after adjustment for calendar time, this association became non-significant (P = 0.573), suggesting possible time-related confounding. CONCLUSION: LAH may improve transferable blastocyst formation in low-grade day 3 cleavage-stage embryos under specific analytical conditions, but the findings were heterogeneous across sensitivity analyses. Because implantation, pregnancy, live birth, neonatal safety, and long-term offspring outcomes were not assessed, these results should be considered hypothesis-generating and require confirmation in multicenter prospective randomized trials.
Abstract as published, via PubMed.
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