Factors Affecting BMI Changes in Mothers during the First Year Postpartum

Area of Science:

• Reproductive Health
• Maternal Nutrition
• Behavioral Science

Background:

• Postpartum weight retention is a significant concern for maternal health.
• Lactation is often associated with greater postpartum weight loss, but individual differences may exist.
• Pre-pregnancy body mass index (BMI) and psychological eating behaviors are potential factors influencing postpartum weight changes.

Purpose of the Study:

• To investigate the impact of infant feeding modality (lactation vs. formula feeding) on postpartum BMI changes.
• To examine how pre-pregnancy BMI status modifies the effect of lactation on postpartum BMI.
• To assess the independent effects of psychological eating behavior traits on postpartum BMI changes.

Main Methods:

• Longitudinal study analyzing anthropometric data from 0.5 months to 1 year postpartum.
• Linear mixed-effects models used to analyze BMI trajectories in lactating and non-lactating mothers.
• Mothers categorized by infant feeding modality and pre-pregnancy BMI status (Healthy Weight, Overweight, Obesity).

Main Results:

• Lactating mothers showed significantly faster initial rates of BMI loss compared to non-lactating mothers, particularly those who were overweight pre-pregnancy.
• Among mothers with pre-pregnancy overweight, 47% of non-lactating mothers gained ≥ 3 BMI units by 1 year postpartum, versus 9% of lactating mothers (p < 0.04).
• Higher dietary restraint, disinhibition, and lower susceptibility to hunger were independently associated with greater postpartum BMI loss.

Conclusions:

• Lactation promotes greater initial postpartum weight loss, with amplified benefits for mothers who were overweight prior to pregnancy.
• Pre-pregnancy BMI status significantly moderates the impact of lactation on postpartum BMI changes.
• Psychological eating behavior traits represent potential modifiable targets for effective postpartum weight management strategies.