A Two-center Study On Factors Influencing Neonatal Umbilical Cord Blood Vitamin D

Objective: To investigate the status of vitamin D,calcium,phosphorus,ALP and PTH in umbilical cord blood of neonates born in the People's Hospital of Naqu region,Tibet(4500m above sea level)and Shengjing Hospital affiliated to China Medical University,Shenyang(500m above sea level),and to explore the relevant influencing factors,so as to to make reasonable recommendations for pregnant women and neonates.Methods: As a prospective cohort study,we collected the serum samples of pregnant women and neonatal umbilical cord blood samples as test subjects,investigated the basic information of maternal,pregnancy and the neonates in the People's Hospital of Naqu,Tibet and Shengjing Hospital affiliated to China Medical University,Shenyang,from June 30,2017 to October 10,2018.Serum vitamin D was detected by electrochemical luminescence immunoassay.Detection of calcium and phosphorus ALP by AU5831 automatic biochemical analyzer.Detection of PTH level by chemiluminescence.At the same time,the age,education of the mother,dietary sun exposure and vitamin D supplementation during pregnancy were investigated.Neonates with severe asphyxia,anemia and congenital genetic metabolic diseases were excluded.Results: Among the 47 neonates in Naqu plateau,39(82.9%)were deficient in vitamin D,7(14.9%)were insufficient in vitamin D,and 1(2.1%)was sufficient.The mean level of umbilical cord blood serum 25(OH)D was(8.49± 4.12)ng/ml,which was significantly lower than that of newborn umbilical cord blood serum 25(OH)D in Shenyang(19.77± 9.57)ng/ml.Among the 248 neonates in Shenyang,51(20.56%)were deficient in vitamin D,91(36.69%)were insufficient in vitamin D,and 106(42.75%)were sufficient in vitamin D.There was a statistically significant difference in the level of vitamin D in neonatal umbilical cord blood between the plateau and the plain(P < 0.05).The risk of neonatal umbilical cord blood vitamin D less than 16.28ng/ml was 6.89 times higher in plateau area than in plain area.There were no statistically significant differences in the effects of neonatal PTH,ALP,calcium and phosphorus,maternal PTH,ALP and calcium levels on umbilical cord blood vitamin D levels(P > 0.05).Pregnant women with a junior school education or below were 20.57 times more likely to have a reduced risk of neonatal umbilical cord blood vitamin D levels than those with a bachelor's degree or above(P<0.05).The risk of neonatal vitamin D reduction in Naqu plateau of Tibet was 6.89 times higher than that in the plain of Shengyang(P<0.05).The risk of vitamin D reduction in neonatal cord blood was 8.83 times that of vitamin D supplementation during pregnancy.For each additional unit of umbilical cord blood calcium,the risk of neonatal vitamin D 16.28ng/ml was reduced by 67%.For each additional unit of vitamin D in pregnant women,the risk of neonatal vitamin D 16.28ng/ml decreased by 16.3%(P < 0.05).There was a significant positive correlation between neonatal serum vitamin D and maternal umbilical cord blood vitamin D level(r=0.75,P < 0.05).For every 1ng/ml increase in maternal serum vitamin D,umbilical cord blood vitamin D increased by 0.623ng/ml.Conclusion: The level of neonatal vitamin D in the People's Hospital of Naqu,Tibet is generally lower than that in the plain area.Vitamin D supplementation during pregnancy can effectively reduce the risk of vitamin D deficiency in newborns.