Influencing Factors Of Vitamin D Level In Very Preterm Infants And Its Influence On Lung Diseases

Part I Vitamin D level and influence factors at birth of very premature infantsObjective:To analyze the levels of vitamin D at birth and the related factors of pregnancy complications by measuring the serum25-hydroxyvitamin D[25-（OH）D]levels in 24 hours after birth of very premature infants with different gestational ages.Methods:100 cases of very premature infants（gestational age<32 weeks）admitted to the neonatal intensive care unit of Affiliated Hospital of Qingdao University from January 2018 to December 2019 were selected as the research objects.2 ml venous blood was collected from all very preterm infants within 24 hours after birth.Serum 25-（OH）D level was determined.According to the serum25-（OH）Dlevel,there were four nutritional status:severe vitamin D deficiency（<10ng/ml）,vitamin D deficiency（≥10～<20 ng/ml）,insufficient vitamin D（≥20～≤30 ng/ml）and suitable vitamin D（>30ng/ml）.Statistical analysis was performed.Results:（1）The level of serum 25-（OH）Dat birth was（9.88±4.48）ng/ml;the proportion of severe vitamin D deficiency,the birth season,moderate deficiency,deficiency and appropriate were 62.00%,35.00%,3.00%and 0.00%,respectively.（2）By univariate analysis,mother’s age,maternal gestational hypertension,and mother’s premature rupture of membranes were related to vitamin D level at birth of very premature infants;（3）Multiple linear regression analysis showed that gestational hypertension was an influencing factors of vitamin D level at birth of very premature infants.Conclusion:（1）the vitamin D level of very premature infants is generally serious at birth.（2）The gestational hypertension are the influencing factors of vitamin D level at birth.Part II The effects of calcitriol on bone metabolism and diseases in very low birth weight infantsObjective:to dynamically monitor the vitamin D level of very preterm infants and to explore its effect on lung diseases of very preterm infants.Method:a total of 126 very preterm infants with gestational age less than 32 weeks admitted to NICU of Affiliated Hospital of Qingdao University from January 2019 to December 2020 were selected.After feeding tolerance,all the very preterm infants were given vitamin AD（vitamin D 500iu,vitamin a 1500iu）,1 capsule per day,and vitamin D3 400IU.Serum 25-（OH）D levels were measured 24 hours after birth,1 month and 2months after birth.According to the level of serum 25-（OH）D,very preterm infants were divided into four groups:severe vitamin D deficiency group:serum 25-（OH）D<10ng/ml;vitamin D deficiency group:serum 25-（OH）D≥10～<20ng/ml;vitamin D deficiency group:serum25-（OH）D≥20～≤30ng/ml;vitamin D appropriate group:serum25-（OH）D>30ng/ml;clinical data of very preterm infants during hospitalization were collected.Statistical analysis was performed.Results:（1）There were no significant differences in gestational age,gestational age group,birth weight,weight group and other general data among very preterm infants（P>0.05）.（2）Vitamin D level and lung disease:there were significant differences in the incidence of respiratory distress syndrome and bronchopulmonary dysplasia among the groups at birth（P<0.05）,and the incidence of severe vitamin D deficiency group was the highest.Spearman correlation analysis showed that there was no significant correlation between different vitamin D levels and the severity of BPD（rs=0.005,P=0.971）.There was no significant difference in 1-minute apger score,5-minute apger score,caffeine use time,noninvasive ventilation time,mechanical ventilation ratio,early pulmonary hypertension,total oxygen use time,patent ductus arteriosus and hospital stay between the two groups（P>0.05）.The proportion of BPD in severe vitamin D deficiency group was significantly increased at 2 months after birth,and the difference was statistically significant（P<0.05）.There was no significant difference in caffeine use time,noninvasive ventilation time and total oxygen use time between different vitamin D groups at 1 month and 2 months（P>0.05）.（3）The vitamin D deficiency rate was 92.86%at birth and 53.17%at 2 months old（or discharged）.The average vitamin D deficiency rate was 7.13±1.73ng/ml at birth,11.39±3.30ng/ml at 1 month old and 16.07±4.03ng/ml at 2 months old.The average level of deficiency group was 13.42±2.49ng/ml at birth,17.65±3.34ng/ml at 1 month old and 25.99±5.42ng/ml at 2 months old;the average level of deficiency group was21.79±2.09ng/ml at birth,17.65±3.34ng/ml at 1 month old and 34.03±3.74ng/ml at 2months old.There was no significant difference in feeding method,parenteral nutrition time,vitamin AD,vitamin D₃addition time,alkaline phosphatase,blood calcium and phosphorus among the three groups（P>0.05）.126 cases of very preterm infants were given 900 IU vitamin D.the results showed that there were significant differences in vitamin D levels among the three groups at 1 month and 2 months（P<0.05）.Conclusion:（1）Vitamin D deficiency at birth increases risk of RDS、BPD,in very premature infants,and vitamin D deficiency at 2 months of age increases BPD’s risk.（2）Very preterm infants were given vitamin D3 after birth,and vitamin D was increased at 1 month and 2 months old.Different levels of vitamin D in preterm infants need individualized supplement.