Vitamin D levels in newborns and association with neonatal hypocalcemia.

OBJECTIVE: Vitamin D has many important functions in our body. Especially in intrauterine and early infancy periods, Vitamin D plays a major role in bone development, growth, and the maturation of tissues such as lung and brain. Fetus is dependent on the mother in terms of Vitamin D and maternal Vitamin D deficiency results in a Vitamin D deficient newborn. The purpose of this study was to determine the levels of Vitamin D in newborns and to investigate the association between Vitamin D status of the baby and neonatal hypocalcemia.

METHOD: Vitamin D, calcium, and parathyroid hormone levels of 750 infants, born between 1 January 2014 and 30 June 2015 and followed in Ondokuz Mayıs University Neonatal Intensive Care Unit were analyzed retrospectively. Blood levels of Vitamin D were checked within 3 days after birth. A 25(OH)D3 level of <10 ng/ml indicated severe, levels between 10 and 20 ng/ml, which indicated moderate and levels between 20 and 30 ng/ml indicated mild Vitamin D deficiency. Serum calcium levels below 8 mg/dl in term infants and below 7 mg/dl in preterm infants were accepted as hypocalcemia. Hypocalcemia that developed within the first week after birth was defined as early, while hypocalcemia after one week were defined as late hypocalcemia.

RESULTS: A total of 44% of the infants in the study were girls, while 56% were boys; 38% were term and 62% were preterm. Average 25(OH)D3 level of all infants was 11.4 ± 10.2 (0-153) ng/ml. Only 30 (4%) infants had normal (>30 ng/ml) 25(OH)D3 levels; 68 (9%) had mild, 234 (31%) had moderate and 418 (56%) had severe vitamin D deficiency. No correlation was found between Vitamin D levels and gender, mother's age, gestational week or birth weight. In 79 (17.2%) preterms, neonatal hypocalcemia was observed. Vitamin D levels of the premature infants who had early neonatal hypocalcemia were statistically significantly lower when compared with those who did not have early neonatal hypocalcemia (p = .02). No significant difference was found between the Vitamin D levels of the term infants who had early neonatal hypocalcemia and those who did not (p= .29). No significant difference was found between the Vitamin D levels of the infants who had late neonatal hypocalcemia and those who did not (in preterm p = .27; in term p = .29).

CONCLUSIONS: Although lack of Vitamin D is preventable and curable, it is an important health problem for newborns in Turkey. In our study, 56% of the infants were found to have severe lack of Vitamin D and lack of Vitamin D was found to be associated with early neonatal hypocalcemia in preterm newborns. However, long-term effects of lack of Vitamin D in infancy are not fully known. In order to be able to prevent neonatal Vitamin D deficiency, 1200 IU/day vitamin D was supplemented to mothers from the 12th gestational week to 6th month of the birth, which was put into effect by the Ministry of Health in 2011, and should be applied by all health workers.