The association between parental overweight and obesity before pregnancy and the development of offspring overweight and obesity in childhood, adolescence and young adulthood

Abstract

Background and aims: Parental obesity is one of the important factors that is strongly linked with the development of offspring obesity. When both parents are obese, the risk of offspring being obese is greater than when one parent is obese. Irrespective of the exposure time of parental overweight and obesity, studies have consistently found that parental overweight and obesity is positively associated with offspring overweight and obesity. Few longitudinal birth-cohort studies have examined pre-pregnancy parental overweight or obesity and whether it is positively associated with offspring overweight and obesity in the long term. Additionally, there are limited studies reporting on the association of prenatal parental obesity with offspring body mass index (BMI) change, and even less is known about the association between long-term post-partum parental BMI change and the risk of offspring obesity. The aim of the current study is to investigate the association between parental obesity and offspring obesity over the life course, using data from birth-cohort studies. This study examines the longitudinal association between prenatal parental BMI and offspring BMI and adiposity in infancy, childhood, adolescence and adulthood. This study also investigates the association between prenatal parental BMI and offspring BMI change in childhood, adolescence and adulthood. Finally, this study adds to research examining the association between 21 years maternal post-partum weight change (PPWC) and the risk of adulthood obesity in offspring. Methods: Data are from two cohorts-Universiti Sains Malaysia Pregnancy Cohort which consists of 145 respondents who provided details of pre-pregnancy parental weight and height and weight and length of offspring at the 12-month follow-up; and the Mater-University of Queensland Study of Pregnancy (MUSP) which consists of 1494 participants with complete weight and height for pre-pregnancy paternal–maternal and offspring weight and height at 5, 14 and 21 years. A series of models were used to test the association between prenatal parental BMI and offspring outcomes to adjust the potential covariates obtained from either cohorts (e.g. maternal factors: gestational weight gain; offspring factors: birth weight, TV watching hours at 14 years). Multiple linear regression, logistic regression and multinomial regression were used (continuous or categorical predictors) to examine the association between pre-pregnancy parental BMI and its categories, and offspring BMI and its categories. Multiple imputation was used to address the issue of missing values in covariates. Generalized estimating equation models were used to examine the longitudinal parental–offspring BMI association in infants and were again used to determine the differential effect size of prenatal parental BMI on childhood, adolescence and adulthood. Finally, we analysed the association between 21 years maternal postpartum BMI change and offspring BMI and waist circumference (WC at 21 years using multiple linear regression and multinomial logistic regression. Results: Major findings are as follows: 1) A significant association was found between maternal BMI and child’s weight for age z-score (WAZ), weight for height z-score (WHZ) and BMI for age z-score (BAZ) at 12 months; although it was attenuated in the fully adjusted model. 2) After adjustment for confounders, for each unit increase in paternal and maternal BMI, the BMI of young adult offspring increased by 0.33 kg/m2 and 0.35 kg/m2, and the waist circumference (WC) increased by 0.76 cm and 0.62 cm, respectively. Offspring at 21 years were at six times more at risk of being overweight/obese (OW/OB) when both parents were OW/OB, compared to offspring of normal-weight parents. 3) A total of 14.7% of the offspring experienced BMI change from normal at 5 years to OW/OB at 14 years, 15.3% from normal at 14 years to OW/OB at 21 years. Overall, the strength of the association of parental BMI with offspring BMI was stronger as offspring became older. When both parents were OW/OB, these associations were stronger than when one parent was OW/OB. 4) In two decades, mothers who had highest weight change were associated with adult offspring’s risk of OW/OB and abdominal obesity with odds of 1.47 (95%CI: 1.08–2.00) and 1.50 (95%CI: 1.10–2.02), respectively. Conclusions: These findings suggest that parental BMI before pregnancy has a long-term association with offspring BMI from early childhood to adulthood. We found mother–offspring and father–offspring associations were of similar strength and direction. There was no offspring male–female differential association. Our study further demonstrated that parental pre-pregnancy nutritional status is an important predictor in early life that influences offspring overweight and obesity throughout life. Intervening to reduce the prevalence of overweight or obesity in early life by targeting parents may have potential benefits. Encouraging adults to maintain a healthy lifestyle in this challenging obesogenic environment may benefit both themselves and subsequent generations. Studies are warranted to further explore parental lifestyle (dietary and physical activities) before pregnancy and the impact of intervention to improve parental lifestyle on offspring outcomes in the long term.