Predictors of longitudinal changes in body composition and body mass index in Brazilian lactating women during the first 8.5 months postpartum

Adriana Divina de Souza Campos, Gabriela Torres Silva, Ana Lorena Lima Ferreira, Amanda Caroline Cunha Figueiredo, Bruna Celestino Schneider, Aline Yukari Kurihayashi, Daniela de Barros Mucci, Jack Ivor Lewis, Sophie Hilario Christensen, Christian Mølgaard, Kim F. Michaelsen, Lindsay H. Allen, Gilberto Kac*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Pregnancy and lactation change women's body composition (BC), but few longitudinal studies have investigated postpartum BC trajectories. We aimed to investigate maternal and infant predictors of maternal body fat (BF), fat mass (FM), fat-free mass (FFM), and body mass index (BMI) trajectories during lactation. Longitudinal study with 234 Brazilian mother-infant dyads followed at 1.0-3.49, 3.5-5.99, and 6.0-8.5 months postpartum. Maternal BC was estimated using bioelectrical impedance at all follow-up points. Longitudinal mixed-effects models with interaction terms with time (weeks postpartum) were employed. FFM declined significantly over weeks postpartum (β = -0.02 kg; 95% CI -0.03, - 0.01). Pre-pregnancy overweight women experienced an increase in all body components (BF: β = 4.91%, 95% CI 3.79, 6.04; FM: β = 6.46 kg, 95% CI 5.26, 7.67; FFM: β = 3.72 kg, 95% CI 2.80, 4.65) and BMI (β = 4.51 kg/m2, 95% CI 3.91, 5.12). Multiparous women showed BMI increases (β = 0.76 kg/m2, 95% CI 0.11, 1.41), and those who delivered by caesarean had FFM (β = 1.87 kg, 95% CI 0.67, 3.07) and BMI (β = 1.39 kg/m2, 95% CI 0.61, 2.18) increases. Women who birthed girls had reductions in FM (β = -1.24 kg, 95% CI -2.41, -0.07) and FFM (β = -0.93 kg, 95% CI -1.84, -0.01). Interactions occurred between maternal age ≥30 years, higher family income, multiparity, and infant sex for BC and BMI trajectories. Maternal age, pre-pregnancy BMI, parity, family income, mode of delivery, and infant sex predict maternal BC and BMI trajectories.

Original languageEnglish
JournalBritish Journal of Nutrition
Pages (from-to)1-33
ISSN0007-1145
DOIs
Publication statusAccepted/In press - 2025

Bibliographical note

Publisher Copyright:
© The Author(s), 2025. Published by Cambridge University Press on behalf of The Nutrition Society.

Keywords

  • lactation
  • maternal BMI
  • maternal body composition
  • postpartum period
  • prospective study

Cite this