Examining maternal and early life risk associations with childhood overweight and obesity

In England, 1 in 10 children aged 4-5 years and 1 in 5 aged 10-11 years are obese, with the prevalence in the most deprived areas being more than twice as that in the least deprived. There is no system-based early identification of childhood obesity risk at the pregnancy stage and onwards. The aim of this project was to examine the associations between risk factors for childhood obesity (including maternal obesity and size at birth) and to develop and validate prediction models on childhood overweight/obesity utilising prospectively collected routine healthcare data at pregnancy, birth and early life. A population-based anonymised cohort of maternal antenatal and birth records for all births registered with University Hospital Southampton, between 2003 to 2018, was linked to child health records including information on postnatal growth, type of feeding and childhood body mass index (BMI) up to the age of 14 years. A systematic review was conducted as part of this work identifying eight prediction models for childhood overweight and obesity. It highlighted methodological limitations in model development, validation and non-standard reporting limiting usability of the published models. In terms of risk factor associations, a large proportion of women (47.7%) gained weight (≥1 kg/m2) between pregnancies. An interpregnancy interval of 12-23 months was associated with the lowest risk of starting the second pregnancy with a higher body weight as well as a lower risk of small for gestational age (SGA) birth in the second pregnancy. Overweight women were at lower risk of recurrent large for gestational age (LGA) birth in the second pregnancy if they lost weight between pregnancies, whereas normal weight and overweight women who gained weight were at increased risk of ‘new’ LGA after having a non-LGA birth in their first pregnancy. In terms of prediction models, these were developed in stages, incorporating data collected at first antenatal booking appointment, birth and early life predictors. Maternal predictors included BMI, highest educational attainment, partnership status, smoking at booking, ethnicity, first language and intake of folic acid supplements. Early life predictors included birthweight and gestational age, sex and weight at 1 and 2 years. Most maternal predictors remained consistent across models indicating that risk could be identified at pregnancy, with more precise estimation at birth/in early-years. Maternal BMI was a key predictor and the high proportion of women gaining weight after pregnancy indicates that preventing weight gain between pregnancies is an important measure to achieve better maternal and offspring outcomes