Impact of Laser-Assisted Hatching on Cognitive and Metabolic Development of Singletons Conceived Through Frozen-Thawed Embryo Transfer: A Matched Cohort Study.

Objective: This study aimed to examine the impact of laser-assisted hatching (LAH) on the physical, metabolic, cognitive and behavioural profiles of singletons conceived through frozen-thawed embryo transfer (FET) at the preschool age.

Design: A matched cohort study.

Setting: The reproductive centre of Women's Hospital, Zhejiang University School of Medicine.

Population: Singletons born to couples with infertility who underwent FET cycles with or without LAH treatment from 2016 to 2019 and were followed up till age 4-6 years in 2023.

Methods: Cognitive and behavioural development was evaluated at the preschool age using the Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV) and the Adaptive Behavior Assessment System, Second Edition (ABAS-II). Statistical analysis was performed using moderated multiple linear regression.

Main Outcome Measures: The full-scale intelligence quotient (FSIQ) and general adaptive composite (GAI).

Results: In total, 120 pairs of mother and child were included in the analysis. No significant differences in age, sex, height, weight, body mass index, blood pressure, thyroid function and metabolic indicators were observed between the two groups. After adjusting for demographics and socioeconomic status, LAH singletons showed FSIQ and GAI scores similar to those of non-LAH singletons.

Conclusions: At 4-6 years of age, the cognitive, metabolic and physical developmental outcomes of preschool children born after LAH treatment were comparable with those of the non-LAH group, indicating that LAH may be considered a safe assisted reproductive technology method. However, further longer and regular follow-ups are needed to validate the findings of this study.