Associations between toddlers’ and parents’ BMI, in relation to family socio-demography: a cross-sectional study

BACKGROUND It is well established that the pregnancy and the first years of life are important for future childhood health and body weight. Even though current evidence suggests that both parents are important for childhood health, the influence that parents' BMI and socio-demography has on toddlers' BMI has so far received little attention. This study aimed to increase our knowledge on the association between toddlers' and parents' BMI, in relation to family socio-demography. Further, the aim was to investigate the interaction between the mothers' and fathers' BMI in relation to their child's BMI. METHODS A total of 697 children with a median age of 18 months (range 16-24 months) participated in the study along with their mothers (n = 697) and fathers (n = 674). As regards representability, our parental sample had a lower proportion of immigrants and the parents were more gainfully employed compared to parents in the rest of Sweden (when the child was 18 months old). The parents completed a questionnaire on parental and child health. Data on parental weight, height, and socio-demographics were recorded along with the child's weight and height measured at an ordinary child health care visit. We used the thresholds for children's BMI that were recommended for surveillance by the Royal College of Paediatrics and Child Health in 2012 based on the WHO reference population. RESULTS Among the toddlers, 33 % had a BMI above the WHO 85(th) percentile and 14 % had a BMI above the WHO 95(th) percentile. The probability of a toddler having a BMI above the WHO 95(th) percentile was significantly increased if either the mother or father was overweight (BMI ≥ 25 kg/m(2)). Furthermore, we found a positive synergistic effect between the mother and father being overweight and their child having a BMI above the WHO 85(th) percentile. No associations were found between the toddlers' BMI and the family's socio-demographics, but there were associations between the parents' BMI and the family's socio-demographics. CONCLUSION High BMI is common even in toddlers in this population. The risk increases if one parent is overweight, and it increases even more if both parents are overweight. The results in this study confirm the importance of considering familial risk factors when examining child health and BMI at ordinary child health care visits already at an early age.