Association between maternal pre-pregnancy body mass index and offspring's outcomes at 9 to 15 years of age.

OBJECTIVE: Maternal pre-pregnancy underweight, overweight and obesity might increase the risk for worse short- and long-term outcome in the offspring. There is a need for further study into the relationship between maternal pre-pregnancy body mass index (BMI) and the combined outcome of physical development, state of health and social behavior in children.

QUESTION: Is maternal pre-pregnancy BMI associated with the child outcome in terms of physical development, state of health and social behavior (school and leisure time behavior) at the age of 9 to 15 years?

METHODS: In the population-based birth cohort study Survey of Neonates in Pomerania (SNIP) children at the age 9-15 years and their families were re-examined by questionnaire-based follow-up. 5725 mother-child pairs were invited to SNiP-follow-up. This analysis is based on the recall fraction of 24.1% (n = 1379). Based on the maternal pre-pregnancy BMI (ppBMI), 4 groups were formed: underweight (ppBMI < 19 kg/m2 , n = 117), normal weight (ppBMI 19-24.99 kg/m2 , n = 913, reference), overweight (ppBMI 25-30 kg). /m2 , n = 237) and obesity (ppBMI > 30 kg/m2 , n = 109).

RESULTS: In the multiple regression model, the BMI-z-score for children of mothers in the underweight group was -0.50 lower, and 0.50/1.07 higher in the overweight/obese group (p < 0.001) compared to reference at median age of 12 years. No differences were found in children of underweight mothers with regard to social behavior (interaction with friends and family), school and sports performance (coded from "very good" to "poor"), other leisure activities (watching television, using mobile phones, gaming), and health (occurrence of illnesses) compared to children of normal weight mothers. In contrast, maternal pre-pregnancy overweight and obesity were associated with lower school and sports performance, and higher screen time (smart phone, gaming, television) compared to children of normal weight mothers.

CONCLUSION: Maternal pre-pregnancy overweight and obesity but not underweight was negatively associated with school performance and leisure time behavior in the offspring at 9-15 years of age.