Impact of maternal pre‐pregnancy overweight on infant overweight at 1 year of age: associations and sex‐specific differences

Summary Background Maternal overweight or obesity (OWOB) is linked to gestational diabetes, fetal macrosomia and higher rates of caesarean delivery. Objectives The study aims to assess whether maternal pre‐pregnancy OWOB is associated with infant overweight in a sex‐dependent manner, independent of microbiota‐altering variables. Methods Weight and length measurements of 955 mother–infant pairs were obtained from the Canadian Healthy Infant Longitudinal Development cohort. Maternal pre‐pregnancy weight was defined as follows: normal, overweight (25 ≤ body mass index 97th percentile were classified as infant overweight at age 1 year. Associations between pre‐pregnancy and infant overweight were determined by linear and logistic regression, adjusting for covariates. Results Maternal pre‐pregnancy OWOB were associated with infant weight‐for‐length and overweight risk at 1 year. Except for pre‐pregnancy obesity, these associations were not attenuated appreciably after adjustment for birth mode, exclusivity of breastfeeding, exposure to antibiotics and infant sex. Yet only boys born to mothers with obesity were three times more likely to become overweight at age 1 independent of microbiota‐altering variables. Pre‐pregnancy obesity was associated with weight‐for‐length in male and female infants. Conclusions Maternal pre‐pregnancy OWOB increases the risk of infant overweight, and this association is more evident in male infants.