Nutritional status of vitamin D and its influencing factors in preterm infants at the early stage after birth

Abstract

Objective To investigate the nutritional status of vitamin D in preterm infants after birth and further explore its possible influencing factors, so as to guide clinical vitamin D therapy and to screen the preterm infants who are at high risk of vitamin D deficiency. Methods Retrospective analysis was conducted in the neonatal department of our hospital from April 21st, 2014 to February 5th, 2016. The serum 25(OH)D level in preterm infants were measured 2 weeks after birth. Data including gender, season of birth, time to initiation of breastfeeding were collected. According to the 25(OH)D levels[25(OH)D≤37.5 nmol/L, 37.5 nmol/L≤50.0 nmol/L, and 25(OH)D>50.0 nmol/L], all the preterm infants were divided into three groups: vitamin D deficiency, insufficiency, and sufficiency groups. The influencing factors of vitamin D in preterm infants were screened by using statistical method. Results The mean 25(OH)D level of 172 preterm infants was (43.1±16.7)nmol/L. In vitamin D deficient, insufficient, and sufficient groups, there were 68 (40%), 50 (29%) and 54(31%) cases of preterm babies, respectively. The mean values of 25(OH)D in these three groups were (27.8±16.7)nmol/L, (42.4±3.4)nmol/L, and (63.0±11.7)nmol/L, respectively. Only the season of birth had significant difference among three groups (P=0.013): 44.2% of the preterm infants born in winter had vitamin D deficiency, which was higher than those in spring (41.7%), summer(33.3%), and autumn (38.1%); 44.2% of the preterm infants born in winter had vitamin D insufficiency, which was much higher than those in spring (30.6%), summer (25.1%), and autumn (19.0%); furthermore, only 11.6% of the preterm infants born in the winter had vitamin D sufficiency, which was much lower than those in spring (27.8%), summer (41.2%), and autumn (42.9%) (OR=4.655, 95% CI=1.716-12.627, P=0.003). Conclusion Vitamin D deficiency in preterm infants 2 weeks after birth is prevalent, and winter birth is a risk factor of vitamin D deficiency and insufficiency in preterm infants. Key words: Vitamin D; Preterm infants; Vitamin D deficiency