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Fetal body composition reference charts and sexual dimorphism using magnetic resonance imaging
Aviad Rabinowich1, Netanell Avisdris2, Bossmat Yehuda3
1Sagol Brain Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Department of Radiology, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel; Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Insights
This study created intrauterine body composition charts for preterm infant nutrition guidance. Sexual differences in fetal body composition are evident in late gestation, with males showing higher fat-free mass.
Area of Science:
- Fetal development research
- Quantitative medical imaging
- Neonatal nutrition science
Background:
- Preterm infant nutrition aims to mimic fetal growth, but intrauterine body composition data is lacking.
- Limited data exists on sex-based differences in fetal body composition during pregnancy.
Purpose of the Study:
- To generate reference charts for intrauterine body composition from 30 to 36+6 weeks postconception.
- To investigate sex-based differences in fetal body composition during late gestation.
Main Methods:
- Retrospective analysis of 197 fetuses using 3T MRI scans.
- Automated segmentation of fetal body and adipose tissue via deep convolutional neural networks.
- Calculation of body mass, fat mass, and fat-free mass metrics; creation of reference charts using GAMLSS.
Main Results:
- Body mass, fat mass, and fat-free mass increased, while fat-free mass percentage decreased with gestational age.
- Reference charts for gestational age and sex-specific percentiles were generated.
- Males exhibited significantly higher body mass, fat-free mass, and fat-free mass percentage compared to females.
Conclusions:
- MRI-derived intrauterine body composition growth charts are valuable for monitoring preterm infant growth.
- Significant sexual dimorphism in body composition is present during the intrauterine period.
Background:
The American Academy of Pediatrics advises that the nutrition of preterm infants should target a body composition similar to that of a fetus in utero. Still, reference charts for intrauterine body composition are missing. Moreover, data on sexual differences in intrauterine body composition during pregnancy are limited.
Objectives:
The objective of this study was to create reference charts for intrauterine body composition from 30 to 36+6 weeks postconception and to evaluate the differences between sexes.
Methods:
In this single-center retrospective study, data from 197 normal developing fetuses in late gestation was acquired at 3T magnetic resonance imaging (MRI) scans, including True Fast Imaging with Steady State Free Precession and T1-weighted 2-point Dixon sequences covering the entire fetus. Deep convolutional neural networks were utilized to automatically segment the fetal body and subcutaneous adipose tissue. The fetus's body mass (BM), fat signal fraction (FSF), fat mass (FM), FM percentage (FM%), fat-free mass (FFM), and FFM percentage (FFM%) were calculated. Using the Generalized Additive Models for Location, Scale, and Shape (GAMLSS) method, reference charts were created, and sexual dimorphism was examined using analysis of covariance (ANCOVA). A P value <0.05 was deemed significant.
Results:
Throughout late gestation, BM, FSF, FM, FM%, and FFM increased, while the FFM% decreased. Reference charts for gestational age and sex-specific percentiles are provided. Males exhibited significantly higher BM (7.2%; 95% confidence interval [95% CI]: 1.9, 12.4), FFM (8.8%; 95% CI: 5.8, 11.9), and FFM% (1.7%; 95% CI: 1, 2.4) and lower FSF (-3.6%; 95% CI: -5.6, -1.8) and FM% (-1.7%; 95% CI: -2.4, -1), (P < 0.001) compared with females, with no significant difference in FM between sexes (P = 0.876).
Conclusions:
MRI-derived intrauterine body composition growth charts are valuable for tracking growth in preterm infants. This study demonstrated that sexual differences in body composition are already present in the intrauterine phase.
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