Independent and synergistic effects of maternal and paternal obesogenic diets on offspring early‐life outcomes in the rat

Independent effects of maternal obesogenic diets on offspring outcomes are acknowledged, but data on paternal and combined maternal-paternal obesity remain limited. We investigated independent and combined maternal-paternal effects of an obesogenic (OB) high-fat, high-sugar diet on offspring outcomes. Male (pat) and female (mat) rats were fed a control diet (CON) or OB diet for 5 weeks pre-mating. Four groups were established: matCON-patCON, matCON-patOB, matOB-patCON and matOB-patOB. Offspring outcomes included birth weight and naso-anal length, survival rates to weaning, weaning weight, retroperitoneal fat mass and plasma leptin. Mating success was reduced in OB-exposed fathers. Male and female offspring from mothers fed the OB diet had lower birth weights. In males, birth weights were further reduced in the matOB-patOB group. Combined maternal-paternal obesity was also associated with shorter body length and higher neonatal mortality in offspring of both sexes. Postnatal survival was lower with maternal obesity and worsened with combined maternal-paternal obesity. At weaning, male offspring exposed to maternal or combined maternal-paternal obesity showed increased body weight, adiposity and plasma leptin concentrations. In females, body weight at weaning was higher across all parental obesogenic diet groups, and increased adiposity and plasma leptin concentrations were observed in maternal and combined maternal-paternal obesity. Parental obesity had independent, combined and sex-specific effects on early-life outcomes, most severe with combined maternal-paternal obesity. These findings emphasise the interacting role of maternal and paternal nutrition in shaping early-life outcomes and highlight the need for research to determine effective strategies to optimise the health of both parents prior to conception.