Fetal growth parameters and birth weight: their relationship to neonatal body composition

Ultrasound Obstet Gynecol. 2009 Apr;33(4):441-6. doi: 10.1002/uog.6317.


Objectives: The main goal was to investigate the relationship between prenatal sonographic parameters and birth weight in predicting neonatal body composition.

Methods: Standard fetal biometry and soft tissue parameters were assessed prospectively in third-trimester pregnancies using three-dimensional ultrasonography. Growth parameters included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), mid-thigh circumference and femoral diaphysis length (FDL). Soft tissue parameters included fractional arm volume (AVol) and fractional thigh volume (TVol) that were derived from 50% of the humeral or femoral diaphysis lengths, respectively. Percentage of neonatal body fat (%BF) was determined within 48 h of delivery using a pediatric air displacement plethysmography system based on principles of whole-body densitometry. Correlation and stepwise multiple linear regression analyses were performed with potential prenatal predictors and %BF as the outcome variable.

Results: Eighty-seven neonates were studied with a mean +/- SD %BF of 10.6 +/- 4.6%. TVol had the greatest correlation with newborn %BF of all single-parameter models. This parameter alone explained 46.1% of the variability in %BF and the best stepwise multiple linear regression model was: %BF = 0.129 (TVol) - 1.03933 (P < 0.001). Birth weight similarly explained 44.7% of the variation in %BF. AC and estimated fetal weight (EFW) accounted for only 24.8% and 30.4% of the variance in %BF, respectively. Skeletal growth parameters, such as FDL (14.2%), HC (7.9%) and BPD (4.0%), contributed the least towards explaining the variance in %BF.

Conclusions: During the late third trimester of pregnancy %BF is most highly correlated with TVol. Similar to actual birth weight, this soft tissue parameter accounts for a significant improvement in explaining the variation in neonatal %BF compared with fetal AC or EFW alone.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adipose Tissue / physiology
  • Adult
  • Anthropometry / methods
  • Birth Weight / physiology*
  • Body Composition / physiology*
  • Female
  • Fetal Development / physiology*
  • Humans
  • Imaging, Three-Dimensional / methods
  • Infant, Newborn
  • Plethysmography
  • Pregnancy
  • Prospective Studies
  • Ultrasonography, Prenatal / methods
  • Young Adult