Trimester-Specific Bioelectrical Impedance Reference Curves in Physiological Pregnancy: Mapping Maternal Body Composition and Hydration Trajectories
7 affiliations
- 1Department of Mother and Child, Mangiagalli Center, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
- 2Department of Clinical and Community Sciences, University of Milan, 20122 Milan, Italy
- 3Unit of Obstetrics, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
- 4School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
- 5Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London SW7 2AZ, UK
- 6Department of Mother and Neonate, Institute for Maternal and Child Health IRCCS “Burlo Garofolo”, 34137 Trieste, Italy
- 7Department of Economics, Quantitative Methods and Business Strategies, University of Milano-Bicocca, 20900 Milan, Italy
Abstract
Background/Objectives: Clinical risk measures such as pre-pregnancy body mass index (BMI) and gestational weight gain do not distinguish the expansion of fluid, lean, and adipose compartments. Standardized obstetric reference curves for bioelectrical impedance analysis (BIA) are lacking. This study aimed to establish longitudinal, trimester-specific BIA reference curves in uncomplicated pregnancies. Methods: This multicenter, prospective, longitudinal cohort study was conducted at three Italian tertiary research hospitals from September 2020 to September 2025. BIA assessments (InBody 270®) were performed at 10–15, 23–25, and 34–37 gestational weeks. Generalized additive models for location, scale, and shape were used to derive reference centiles and BMI-conditioned contour plots for total body water, lean mass, fat mass, and visceral fat level. Pregnancies with complications or incomplete longitudinal data were excluded from the primary reference cohort. Results: Among 442 healthy pregnant women, all parameters increased progressively across gestation. Each 1-unit increase in pre-pregnancy BMI was associated with a larger shift in fat mass (1.88 kg; 95% CI, 1.77–1.99) than in total body water (0.47 L; 95% CI, 0.38–0.57). Conclusions: These multicenter, BMI-conditioned, trimester-specific BIA reference curves provide normative benchmarks for maternal hydration and body composition and may support the identification of early deviations from physiological gestational trajectories.
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BibTeX
@article{martino2026trimesterspecific,
title = {{Trimester-Specific Bioelectrical Impedance Reference Curves in Physiological Pregnancy: Mapping Maternal Body Composition and Hydration Trajectories}},
author = {Daniela Denis Di Martino and Elisa Sabattini and Lucrezia Viscioni and Serena Cerri and Tatjana Radaelli and Sara Ornaghi and Jennifer Belfiore and Tamara Stampalija and Roberto Nuredini and Giulia Privitera and Gabriele Tinè and Enrico Ferrazzi and 3P Study Group Collaborators},
journal = {Nutrients},
year = {2026},
month = oct,
doi = {10.3390/nu18203341},
url = {https://www.mdpi.com/2072-6643/18/20/3341},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Trimester-Specific Bioelectrical Impedance Reference Curves in Physiological Pregnancy: Mapping Maternal Body Composition and Hydration Trajectories
AU - Daniela Denis Di Martino
AU - Elisa Sabattini
AU - Lucrezia Viscioni
AU - Serena Cerri
AU - Tatjana Radaelli
AU - Sara Ornaghi
AU - Jennifer Belfiore
AU - Tamara Stampalija
AU - Roberto Nuredini
AU - Giulia Privitera
AU - Gabriele Tinè
AU - Enrico Ferrazzi
AU - 3P Study Group Collaborators
PY - 2026
DA - 2026/10/01
JO - Nutrients
DO - 10.3390/nu18203341
UR - https://www.mdpi.com/2072-6643/18/20/3341
AB - Background/Objectives: Clinical risk measures such as pre-pregnancy body mass index (BMI) and gestational weight gain do not distinguish the expansion of fluid, lean, and adipose compartments. Standardized obstetric reference curves for bioelectrical impedance analysis (BIA) are lacking. This study aimed to establish longitudinal, trimester-specific BIA reference curves in uncomplicated pregnancies. Methods: This multicenter, prospective, longitudinal cohort study was conducted at three Italian tertiary research hospitals from September 2020 to September 2025. BIA assessments (InBody 270®) were performed at 10–15, 23–25, and 34–37 gestational weeks. Generalized additive models for location, scale, and shape were used to derive reference centiles and BMI-conditioned contour plots for total body water, lean mass, fat mass, and visceral fat level. Pregnancies with complications or incomplete longitudinal data were excluded from the primary reference cohort. Results: Among 442 healthy pregnant women, all parameters increased progressively across gestation. Each 1-unit increase in pre-pregnancy BMI was associated with a larger shift in fat mass (1.88 kg; 95% CI, 1.77–1.99) than in total body water (0.47 L; 95% CI, 0.38–0.57). Conclusions: These multicenter, BMI-conditioned, trimester-specific BIA reference curves provide normative benchmarks for maternal hydration and body composition and may support the identification of early deviations from physiological gestational trajectories.
SN - 2072-6643
ER -