1021 Bone Strength Measured by Quantitative Ultrasound in Newborn Infants in Taiwan

Background and aims: The measurement of speed of sound (SOS) by quantitative ultrasound could be used to assess bone strength in newborn infants. There is few data about bone strength in newborn infants in Taiwan. Our objective was to determine the bone strength measured by SOS of newborns in Taiwan and also to evaluate the factors associated with bone strength at birth. Methods: Full term and preterm infants admitted to baby room or neonatal ward of Kaohsiung Medical University Hospital were enrolled. Birth chart and maternal history were recorded. SOS measured by quantitative ultrasonography was performed at the left tibia in one week after birth. Results: A total of 513 infants were enrolled in this study. For term infants (more than 37 weeks), mean SOS was 2964.8 m/s (SD 104.1 m/s), which significantly higher than infants with gestational age 32-36 weeks (mean ± SD, 2951.6 ± 99.9 m/s) and gestational age less than 32 weeks (2867.2 ± 123.7 m/s). In all infants, there was a significant positive correlation between SOS and gestational age, birth weight, birth length, and head circumference. Male babies had higher SOS than female babies (p=0.004). Multiple regression analysis revealed gender, gestational age and birth weight were two important factors influencing SOS at birth. The procedure was well tolerated in all infants. No adverse effects were found. Conclusions: Bone strength measured by quantitative ultrasound in newborn infants are correlated with gender, gestational age and birth anthropometrics, but not related to maternal factors, and seasons of birth.