Media
Monday April 7, 2025
NIH results could lead to more effective monitoring of twin pregnancies.
What
The twins – more registered at birth, on average, than the singles – began to be smaller during pregnancy than what was previously known, according to a study carried out by researchers from the National Institutes of Health (NIH). The ultrasound study revealed that twins have less adipose tissue and less muscle mass than the singons starting at 15 weeks of pregnancy. If the results are confirmed by additional research, the results could provide information to guide doctors in monitoring and management of twin pregnancies.
The researchers analyzed the data from the previous ultrasound studies fetal development in the uterus. The analysis included 3D ultrasounds of 2,604 Singleton pregnancies and 315 twins. All twin pairs had individual placentas. The twin pairs which shared a placenta were not included in the analysis.
From 15 weeks, the thigh volumes were much smaller for twins than the singons. The twins had volumes of fatty thighs and lean smaller than the singons. They also had a fat and lower thigh than the singles, having proportionally 2.7 to 4.2% less fat from 15 to 37 weeks. Previous studies on twin growth in the uterus involved 2D ultrasound analyzes and had documented a decrease in twin growth compared to the singons that at the beginning of the 3RD Quarter (28 to 40 weeks).
Scientists do not think that early twins were born early resulting from increased competition for nutrients, as their placentas should have been sufficiently developed to provide necessary resources until the third quarter. On the contrary, they hypothesize that the small size of the twins at the beginning of pregnancy could be an adaptation to adapt to the need for an increase in the resources of two fetuses later in pregnancy.
The study was conducted by Jessica Gleason, Ph.D. and Katherine Grantz, MD, NIH Eunice Kennedy Shriver National Institute for Children’s Health and Human Development and their colleagues. It appears in Jama Pediatrics.
WHO
Jessica Gleason, Ph.D., a perinatal epidemiologist, is available to comment.
Article
Gleason JL, et al. Composition of the fetal body in twins and singles. Jama Pediatrics. DOI: https://doi.org/10.1001/jamapediatrics.2025.0116 (2025)
On the Eunice Kennedy Shriver National Institute for Children’s Health and Human Development (NICHD): Nichd conducts research and training to understand human development, improve reproductive health, improve the lives of children and adolescents and optimize capacities for all. For more information, visit https://www.nichd.nih.gov.
On the National Institutes of Health (NIH):The NIH, the country’s medical research agency, includes 27 institutes and centers and is a component of the American department of health and social services. NIH is the main federal agency that leads and supports basic, clinical and translational medical research, and studies the causes, treatments and remedies for common and rare diseases. For more information on NIH and its programs, visit www.nih.gov.
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