Serum level of vitamin D in preterm infants and its association with premature-related respiratory complications: a case-control study

Background and aim Prematurity and related problems, especially respiratory distress, are one of the main challenges for neonatal medicine. The aim of this study was to compare vitamin D levels in preterm infants with, and those without respiratory distress. Methods This case-control study was conducted in Ghaem and Emam Reza Hospitals in Mashhad (Iran) from 2015 to 2016. In this study, we examined 160 preterm infants weighing less than 2000 grams and born at less than 34 weeks' gestation. Serum vitamin D levels were measured in preterm infants without- and those with respiratory distress, and their mothers. Neonatal characteristics, including age, sex, birth weight, gestational age, Apgar score and needs for oxygen, resuscitation, ventilation and surfactant were documented. The data were analyzed using SPSS version 16.0. Results Means serum level of maternal vitamin D in control and case groups were 16.66±14.29 ng/dl and 21.23±15.19 ng/dl, respectively (p=0.029). In addition, mean serum level of neonatal vitamin D in control and case groups were 11.69±8.66 ng/dl 17.9±12.55 ng/dl, respectively (p=0.001). Vitamin D levels in premature neonates without respiratory distress and their mothers were significantly different from other preterm neonates with respiratory distress (p=0.029). There was a direct correlation with neonatal and maternal vitamin D levels (r=0.713, p=0.001). The duration of hospitalization (p=0.001), gestational age (p=0.073), birth weight (p=0.001), one- and (p=0.001) five-minute (p=0.001) Apgar scores and head circumference (p=0.002) had significant relation with vitamin D levels in neonates. Death (12.5%) and pneumothorax (7.5%) were the main complications among cases with respiratory distress. Conclusion According to the results of present research, neonatal vitamin D levels have a significant association with respiratory distress syndrome and maternal vitamin D levels.