Vitamin D level at birth and influencing factors in preterm infants / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate vitamin D level at birth and possible influencing factors in preterm infants.</p><p><b>METHODS</b>A total of 600 preterm infants were enrolled, and venous blood samples were collected within 24 hours after birth to measure the serum level of 25-hydroxyvitamin D [25(OH)D]. The effect of sex, birth weight, birth season, gestational age, mother's age, body mass index (BMI) in early pregnancy, delivery mode, and complications during pregnancy on serum 25(OH)D level was analyzed.</p><p><b>RESULTS</b>The rates of vitamin D deficiency, insufficiency, and sufficiency were 42.0%, 38.7%, and 19.3% respectively. The preterm infants born in summer and autumn had a significantly higher serum 25(OH)D level than those born in winter (P<0.05) and a significantly lower incidence rate of vitamin D deficiency than those born in spring and winter (P<0.003). Compared with those whose mothers were aged <30 years, the infants whose mothers were aged ≥30 years had a significantly higher serum 25(OH)D level (P<0.05) and a significantly lower incidence rate of vitamin D deficiency (P<0.017). Compared with those whose mothers were overweight or had normal body weight, the infants whose mothers were obese had a significantly lower serum 25(OH)D level (P<0.05) and a significantly higher incidence rate of vitamin D deficiency (P<0.006). Compared with those whose mothers had no preeclampsia, the infants whose mothers had preeclampsia during pregnancy had a significantly lower serum 25(OH)D level (P<0.05) and a significantly higher incidence rate of vitamin D deficiency (P<0.017). The multivariate analysis showed that birth in winter and spring, mother's age <30 years, and early-pregnancy BMI ≥28 kg/mwere risk factors for vitamin D deficiency (P<0.05).</p><p><b>CONCLUSIONS</b>There is a high prevalence of vitamin D deficiency in preterm infants. Vitamin D supplementation should be given to the preterm infants with high-risk factors for vitamin D deficiency.</p>

Examination of infant bone status with quantitative ultrasound at birth / 中华儿科杂志

<p><b>OBJECTIVE</b>Quantitative ultrasound (QUS) is a new method of evaluating Children's bone status, including bone mineral density and bone strength. The bone nutrition during fetal and early neonatal period is very important for the human bone development of whole life. The objective of this study was to evaluate the clinical application of QUS for newborn infants and to obtain the QUS data for normal neonates including premature infants.</p><p><b>METHODS</b>An ultrasound bone sonometer, Omnisense, produced by Sunlight company of Israel, was applied to measure the bone speed of sound (SOS) of tibia in 157 neonates including 68 premature infants in the first week of life.</p><p><b>RESULTS</b>(1) No significant difference in SOS was found between male (n = 88, SOS = 2968 +/- 115 m/s) and female infants (n = 69, SOS = 2956 +/- 105 m/s) (P = 0.524). The SOS of premature infants (n = 68, mean gestational age 33.0 +/- 2.5 weeks) and full-term infants (n = 89, mean gestational age of 39.4 +/- 1.3 weeks) were 2935 +/- 96 m/s and 2984 +/- 116 m/s, respectively, at birth and there was significant difference between them (P = 0.005). (2) There were significant differences of SOS in neonates who were born in different seasons (F = 4.377, P = 0.005); the significant difference remained (F = 3.933, P = 0.010) after the influences of gestational age and birth weight were eliminated. The SOS in neonates born in spring (March, April and May) and summer (June, July and August) were significantly lower than that of those born in autumn (September, October and November) and winter (December, January and February). The SOS in neonates born in summer was about 2.3% (75/2999) was lower than that of those born in winter. (3) Significant difference of SOS was observed between neonates with different birth weight [< 1500 g (n = 11), SOS = 2968 +/- 115 m/s; and > 2500 g (n = 86), SOS = 2980 +/- 113 m/s; P = 0.042]. (4) Significant correlations were found between SOS and gestational age (r = 0.270, P = 0.005), and between bone SOS and birth weight (r = 0.232, P = 0.015) in appropriate for gestational age (AGA) infants (n = 109); however, no such significant correlations were found in small for gestational age (SGA) infants or large for gestational age (LGA) infants. Multiple regression analysis showed that gestational age and the birth season were two important factors which may contribute to bone SOS of neonates at birth (n = 157, F = 8.515, P < 0.001, adjusted R(2) = 0.141), when the analysis was carried out with SOS as dependent variable and gestational age, birth weight, chronological age, calf length and the birth season as independent variables.</p><p><b>CONCLUSION</b>QUS is a new method which is suitable for evaluating the bone status of neonates and it is free of radiation, non-invasive, the machine is portable and easy to manipulate at infant bed side. The present study suggests the need for particular care for the bone status in premature infants and supplement of vitamin D in pregnant women.</p>