Association of maternal pre-pregnancy body mass index with resilience and prosociality of the offspring aged 6–7 years old: a population-based cohort study in Japan

The association between maternal pre-pregnancy obesity and child behavior problems has been widely researched, leaving a gap in understanding the positive aspects of children’s mental health. The present study aimed to investigate the association between maternal pre-pregnancy body mass index (BMI) and resilience and prosociality among 6–7 year-old children in Japan. A retrospective cohort study was conducted using data from the Adachi Child Health Impact of Living Difficulty (A-CHILD) study, a population-based study in 2017 and 2019 including all first-grade students in public schools in Adachi, Tokyo, Japan (n = 7328, response rate = 84.7%). Resilience and prosociality were measured by the Children’s Resilient Coping Scale and the Strength and Difficulties Questionnaire, respectively. Maternal pre-pregnancy weight and height were reported based on the Mother and Child Health Handbook, and BMI was categorized as underweight (BMI < 18.5), normal weight (BMI 18.5–24.9), overweight (BMI 25.0–29.9), and obesity (BMI ≥ 30). Linear regression models were employed to control for covariates. Maternal pre-pregnancy obesity was found to be negatively associated with child resilience (coefficient: − 3.29; 95% CI − 6.42–-0.15), while maternal underweight was negatively associated with child prosociality (coefficient: − 0.12; 95% CI − 0.24–-0.005) compared to mothers of pre-pregnancy normal BMI. Perinatal factors, such as gestational weight gain, gestational age, and birth weight, did not mediate the association. Our findings suggest that maternal pre-pregnancy obesity is linked to decreased resilience and maternal underweight is linked to decreased prosociality in children aged 6–7 years. Maintaining an appropriate BMI range before pregnancy may be crucial for enhancing resilience and prosociality of offspring.