Maternal Pregestational Nutritional Status and Growth of Breastfed Infants: Findings from a Cohort Study in Brazil

Introduction: Rapid childhood weight gain increases future health risks like obesity. Exclusive breastfeeding is protective, but factors influencing infant growth in the first 6 months, including maternal nutrition, need further study.

Aim: To evaluate the association of maternal pregestational nutritional status with the growth trajectories of exclusively breastfed infants.

Methods: A cohort study followed postpartum women with full-term singleton infants from 1 to 6 months at a breastfeeding center in São Paulo (2022–2024). Participants were grouped by pregestational BMI: normal, overweight, and obese. Infants’ weight and length were measured monthly, and WHO-based z-scores for BMI-for-age, weight-for-age, and height-for-age were calculated and compared. The study was approved by the UNIFESP Ethics Committee.

Results: Infants born to obese mothers exhibited significantly greater increases in BMI-for-age z-scores (mean difference: 0.82; 95% CI: 0.25 to 1.39) and weight-for-age z-scores (mean difference: 0.64; 95% CI: 0.13 to 1.16) at six months of age, compared to those born to mothers with normal weight. These differences became apparent from the third month of life. No significant difference was observed in height-for-age z-scores between the groups (mean difference: 0.06; 95% CI: –0.40 to 0.53).

Conclusion: Maternal obesity was associated with accelerated weight gain in infants after the third month, suggesting a potential influence of maternal metabolic programming on early growth trajectories. However, breastfeeding appeared to help regulate weight gain among infants born to mothers with varying nutritional statuses during the first three months of life.