Objective: Previous studies have shown strong parental influences on adolescent overweight. However, longitudinal data is scarce on gender-specific effects of parental body mass index (BMI) on ...offspring overweight. The objective of this study was to examine the associations of parental pre-pregnancy BMI, weight change, BMI and BMI class transition 16 years after pregnancy with the BMI of their 16-year-old children. Subjects and methods: The study population was derived from the general population-based Northern Finland Birth Cohort 1986. A total of 4788 child-mother-father trios (2325 boys, 2463 girls) were analysed. Weight and height of the adolescents were measured and overweight and obesity defined according to the International Obesity Task Force. For the parents, self-reported data were obtained and overweight and obesity defined according to the World Health Organization. Associations of parental BMI status and weight change with offspring BMI were assessed using binary logistic regression analyses stratified by gender and adjusted for parental age and education. Results: Children whose both parents were overweight or obese both before pregnancy and after 16-year follow-up had a strikingly high risk of overweight at age 16 years (boys odds ratio (OR) 5.66 95% confidence interval (CI) 3.12, 10.27; girls OR 14.84 95% CI 7.41, 29.73). Parental pre-pregnancy obesity strongly predicted offspring overweight (mother-son OR 4.36 95% CI 2.50, 7.59; mother-daughter OR 3.95 95% CI 2.34, 6.68; father-son OR 3.17 95% CI 1.70, 5.92; father-daughter OR 5.58 95% CI 3.09, 10.07). Conclusion: Parental overweight conveys a major risk for overweight in children for which both parents' long-term overweight (BMI 25 kg m-2 before pregnancy and after 16-year follow-up) was the strongest single predictor. Preventing intergenerational transmission of obesity by helping parents to maintain a healthy weight is an essential target for public health.
