No changes in weight and body fat in lactating adolescent and adult women from Mexico.

Objective: To evaluate changes in weight and body fat of Mexican adolescent compared to those of adult lactating women from the Northwest (NM) and Central (CM) regions of Mexico in the first trimester postpartum.

Methods: A prospective design was used to evaluate 41 exclusively breastfeeding women (21 adolescents and 20 adults) recruited 1-2 days after delivering a healthy singleton at the Hospital Infantil del Estado de Sonora (Northwest Mexico) and Instituto Nacional de Perinatología, in Mexico City. Socioeconomic status, height, body weight and composition, dietary intake, physical activity, and milk volume (quantified by deuterium dilution method) were measured at the 1st and 3rd month postpartum.

Results: Women did not lose weight throughout the first trimester postpartum. Mean postpartum weight retention at the end of the study was 3.8 kg. No differences in weight and body mass index (BMI) were found between adolescent and adult women in both periods. Energy and macronutrient intakes, physical activity and milk volume were similar between the two groups of women. In both periods, adolescents from the CM region had lower weight, BMI, and body fat than adolescents from the NM region (P<0.05). At the 3rd month, pregestational weight (P < 0.0001) was a predictor of BMI, and region (P < 0.05) and milk volume (P < 0.01) were associated with percentage of body fat.

Conclusions: Exclusively breastfeeding for 3 months did not reduce weight or body fat in the Mexican population of this study. Efforts to avoid weight retention in the lactation period may contribute to prevent overweight and obesity in women.