Authors say this finding may suggest twins’ smallness as an early adaptive mechanism
By Lori Solomon HealthDay Reporter
THURSDAY, April 17, 2025 (HealthDay News) — Twins have proportionally less fat tissue accumulation in utero compared with singletons as early as 15 weeks of gestation, according to a study published online April 7 in JAMA Pediatrics.
Jessica L. Gleason, Ph.D., from the Eunice Kennedy Shriver National Institute of Child Health and Human Development in Bethesda, Maryland, and colleagues evaluated longitudinal fetal soft tissue development. The analysis included data from ultrasound scans at 15 to 37 weeks of gestation from 2,604 singleton and 171 twin pregnancies (315 fetuses).
The researchers found that mean twin abdominal measurements were significantly smaller than those of singletons between 25 and 37 weeks of gestation for area (difference at 25 weeks, −48.6 mm2; difference at 37 weeks, −480.5 mm2) and between 27 and 37 weeks for maximum abdominal subcutaneous tissue thickness (difference at 27 weeks, −0.13 mm; difference at 37 weeks, −0.40 mm). Fractional thigh volumes were significantly smaller for twins (mean fractional thigh volume difference, −0.11 cm3; mean fractional fat thigh volume difference, −0.08 cm3) relative to singletons, beginning at 15 weeks and persisting through 37 weeks (mean fractional thigh volume difference, −7.55 cm3; mean fractional fat thigh volume difference, −5.60 cm3). Similarly, mean fractional lean thigh volume was significantly smaller for twins at 15 to 16 and 23 to 36 weeks. Compared with singletons, for the ratio of fractional fat thigh volume to fractional thigh volume, twins had a 2.7 to 4.2 percent smaller fat percentage between 15 and 37 weeks.
“Persistent findings of smaller twin sizes and less fat accumulation across pregnancy support the concept of an early evolutionary adaptive process in otherwise uncomplicated dichorionic twin growth,” the authors write.
Several authors disclosed ties to relevant organizations.
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