Takeo Fujiwara

Objective To identify the optimal gestational weight gain (GWG) thresholds for behavioral problems and prosocial behavior in 6‐ to 7‐year‐old children. Methods A retrospective cohort study was conducted using data from the Adachi Child Health Impact of Living Difficulty study, including all first‐graders in public schools in Adachi, Tokyo, in 2017, 2019, and 2021 ( n = 11 048, response rate = 80.1%). GWG was based on clinical records in the Mother and Child Health Handbook. Total difficulties and prosocial behavior were assessed using the Strength and Difficulties Questionnaire. Logistic regression models with restricted cubic splines, and quintile categories were employed to examine the association of GWG with the clinical range of total difficulties and prosocial behavior, controlling for covariates. Results The association between GWG and total difficulties exhibited a reverse J‐shaped pattern, with low GWG, but not high GWG, increasing the risk (odds ratio [OR] 1.20, 95% confidence interval [CI] 1.01–1.42, P = 0.039 for GWG < 7 kg; OR 1.03, 95% CI 0.85–1.24, P = 0.786 for GWG > 14 kg), referencing the median (10 kg). High GWG was associated with a lower risk of problems in prosocial behavior (OR = 0.77, 95% CI 0.62–0.95, P = 0.017 for GWG > 14 kg; OR 1.06, 95% CI 0.88–1.27, P = 0.532 for GWG <7 kg). Conclusion GWG less than 7 kg may increase the risk of total difficulties, whereas GWG over 14 kg may serve as a protective factor for prosocial behavior in 6‐ to 7‐year‐old children.