The phenotype of babies born with extremely low body weight at term-equivalent age (38–40 weeks)
AbstractNutritional support and early postnatal growth of a premature baby have a significant impact on future health. Feeding options for preterm infants and the ideal growth pattern for a preterm infant remain the subject of active study and debate.
The aim of our study was to assess the physical development, including the body composition, and the features of the phenotype of extremely low body weight infants (ELBW) by postconceptual age (PCA) of full-term pregnancy in comparison with full-term newborns.
Material and methods. The study included 36 ELBW infants [group 1 –18 babies whose physical development at birth was appropriate for gestational age (GA); group 2 – 18 babies small in weight or in weight and length for GA, and group 3 – 35 full-term newborns]. Anthropometric data of babies at birth and postnatal growth of premature babies were assessed according to the scales of international growth standards INTERGROWTH‑21st. In preterm infants at PCA 38–40 weeks, weight and length of the body, head circumference, thickness of the skin-fat fold on the abdomen, as well as the value of fat-free mass and percentage of fat in the body composition were measured by air plethysmography using the body composition analyzer for infants PEA POD (LMi, USA). Measurements were performed in full-term babies aged 1–7 days of life (on average – on the 3rd day).
Results. By the 40th week of PCA in ELBW infants of groups 1 and 2, body weight and length, as well as the value of lean body mass, were significantly lower than in full-term newborns, while the percentage of fat was significantly higher. A distinctive feature of ELBW infants group 1 was a greater thickness of the skin-fat fold on the abdomen than in full-term newborns. Anthropometric data of ELBW infants of the 2nd group by the 40th week of PCA were lower than in the 1st and 3rd groups, and more often did not reach the 10th centile. In comparison with full-term newborns, the phenotype of ELBW babies by 40 weeks of PCA was characterized by: lower body weight and length, relatively short limbs, a relatively large head with protruding frontal and parietal eminences, and a satisfactory thickness of the skin-fat fold on the abdomen.
Conclusion. Assessment of the physical development of premature babies must be carried out, taking into account specially created international standards for premature babies. The postnatal growth of premature babies is fundamentally different from the patterns of intrauterine growth of the fetus, which leads to pronounced phenotypic differences between ELBW infants at the PCA of 40 weeks and full-term newborns.
Keywords:preterm infants; extremely low birth weight; postnatal growth; body composition; phenotype
Funding. The study had no sponsor support.
Conflict of interest. The authors declare no conflict of interest.
For citation: Narogan M.V., Ryumina I.I., Markelova M.M., Perepelkina A.E., Baibarina E.N. The phenotype of babies born with extremely low body weight at term-equivalent age (38–40 weeks). Neonatologiya: novosti, mneniya, obuchenie [Neonatology: News, Opinions, Training]. 2024; 12 (1): 10–7. DOI: https://doi.org/10.33029/2308-2402-2024-12-1-10-17 (in Russian)
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