[Reference values for bone strength assessed by quantitative ultrasound early after birth in term and preterm neonates].

Aim: To obtain reference values for bone strength assessed early after birth for term and preterm neonates in Portugal.
Methods: Speed of sound (SOS) (m/s) was measured using the quantitative ultrasound method in a systematic sample of appropriate-for-gestationalage term and preterm neonates, within the first two and five days after birth, respectively. Homogeneity of values between genders and between gestational age groups was assessed.
Results: A sample of 158 neonates was enrolled, 34 full-term and 124 preterm (26-41 weeks of gestation), birth weights of 595g-4195g, 84 males (53.2%) and 20 twins (10.8%). The mean of the SOS significantly increases with gestational age. Reference values of SOS for gestational age groups are provided as 10th, 25th, 50th, 75th and 90th centiles without gender distinction.
Conclusion: Reference values for SOS early after birth are made available for term and preterm appropriate-for-gestational age neonates, reflecting the intrauterine bone status, a baseline for follow-up studies on bone strength in Portugal.