Analysis Of Vitamin D Level And Its Influencing Factors In Exclusively Breast-fed Infants And Their Mothers

Objective:The serum vitamin D levels of 1-6-month-old exclusively breastfed infants and their mothers were measured,and compared with the sex,age,body weight,time of outdoor activities and vitamin D supplementation of exclusive breastfed infants,whether the mother took vitamin D and calcium supplements during pregnancy,the average daily milk intake and the time of outdoor activities.To compare whether mothers take vitamin D and calcium during lactation,average daily milk intake and outdoor activity time,to analyze the related factors of exclusive breastfeeding infants and their mothers’ vitamin D levels and the correlation between their serum vitamin D levels,in order to understand the serum vitamin D concentration of exclusive breast-fed infants and their mothers in Kunming,so as to provide basis for the prevention of infant nutritional rickets.Methods:Chemiluminescence immunoassay was used to detect the venous blood 25-hydroxyvitamin D levels of 48 exclusively breastfed infants and their mothers who underwent physical examination in the Children’s Health Care Clinic of the second affiliated Hospital of Kunming Medical University from May 2020 to January 2021.48 exclusively breastfed infants and their mothers were investigated by questionnaire to investigate the related factors of vitamin D deficiency.SPSS26.0 statistical software was used to analyze the data.Results:1.In 48 samples,the median blood 25-(OH)D of exclusively breast-fed infants was 16.7ng/ml.The proportion of normal serum vitamin D level(>20ng/ml)was 41.7%(20 cases),and the proportion of deficiency and deficiency(≤20ng/ml)was 58.3%(28 cases).The median of 25-(OH)D in lactating mothers was 22.6 ng/ml.Among them,the proportion of normal serum vitamin D level(>30ng/ml)was 14.6%(7 cases),and the proportion of deficiency and deficiency(≤30ng/ml)was 85.4%(41 cases).2.In 41 infants who received vitamin D supplementation(about 400IU/days,>1 month)after birth,the median level of blood 25-(OH)D was 19.60 ng/ml,and in 7 cases without vitamin D supplementation,the median level of 25-(OH)D was 13.23 ng/ml,and there was significant difference between the two groups(P<0.05).The median of serum 25-(OH)D was 19.60 ng/ml in 41 infants who were given vitamin D supplementation after birth,and 13.23 ng/ml in 7 infants without vitamin D supplementation(P<0.05).In 48 exclusively breastfed mothers,the median blood 25-(OH)D of infants who received vitamin D and calcium supplements during pregnancy(about 620IU/days+600mg calcium for 3 days,>3 months)and those who did not receive vitamin D and calcium supplements during pregnancy were 20.10ng/ml and 13.31 ng/ml,respectively.There was significant difference between the two groups(P<0.05).The median blood 25-(OH)D of breast-feeding mothers who received vitamin D and calcium supplementation during lactation(about 620IU/days+600mg calcium daily,>3 months)and those who were not supplemented with vitamin D and calcium during lactation were 25.80ng/ml and 16.67 ng/ml,respectively.There was significant difference between the two groups(P<0.05),and the median of blood 25-(OH)D of infants fed with vitamin D and calcium supplementation during lactation and those who were not supplemented with vitamin D and calcium during lactation were significantly different between the two groups.The median of blood 25-(OH)D of exclusively breast-fed infants whose daily outdoor activity time was less than 2 hours and more than 2 hours was 16.42ng/ml and 29.10 ng/ml,respectively,and there was significant difference between the two groups(P<0.05).In exclusive breastfeeding infants,the median of blood 25-(OH)D born in autumn and spring was 12.93ng/ml and 24.65 ng/ml,respectively,and there was significant difference between the two groups(P<0.05).The blood vitamin D levels of exclusively breast-fed infants were compared among different ages,birth weight,sex,mother’s average daily milk intake during pregnancy and lactation,and the daily outdoor activities during pregnancy and lactation.The difference was not statistically significant(P=0.07,0.293,0.452,0.513,0.119,0.115,0.330).The above significant factors were analyzed by binary logistics regression analysis:vitamin D supplementation after birth and maternal vitamin D and calcium supplements during pregnancy and lactation were protective factors for normal vitamin D levels in exclusive breast-fed infants,and winter birth was a risk factor for normal vitamin D levels.3.In 48 exclusively breastfed mothers,the median of serum 25-(OH)D was 23.10g/ml and 13.31 ng/ml in pregnant women who received vitamin D and calcium supplements(about 600IU/days+600mg calcium,>3 months)and those who did not take vitamin D and calcium supplements during pregnancy.There was significant difference between the two groups(P<0.05).The median of 25-(OH)D in breast-feeding mothers who received vitamin D and calcium supplementation during lactation(about 620IU/days+600mg calcium daily,>3 months)and mothers without vitamin D and calcium supplementation during lactation were 29.78ng/ml and 17.70ng/ml,respectively,and there was significant difference between the two groups(P<0.05).The results showed that the median of 25-(OH)D in breast-feeding mothers without vitamin D and calcium supplementation was significantly higher than that in breast-feeding mothers without vitamin D and calcium supplementation.The median of blood 25-(OH)of mothers with average daily milk intake<250ml and≥250ml was 19.00ng/ml and 23.80ng/ml,respectively,and there was significant difference between the two groups(P<0.05).The serum vitamin D levels of exclusive breastfeeding mothers were not significantly different among different ages,BMI,average daily milk intake during pregnancy,daily outdoor activities during pregnancy and lactation,P values were 0.357,0.252,0.335,0.417 and 0.539,respectively.The above significant factors were analyzed by binary logistics regression analysis:vitamin D and calcium supplementation during lactation were protective factors for normal vitamin D levels in exclusive breastfeeding mothers.4.The blood 25-(OH)D level of exclusively breast-fed infants was positively and weakly correlated with the blood 25-(OH)D level of their mothers.(ritual 0.316 P<0.05).Conclusions:1.The vitamin D levels of exclusively breast-fed infants and their mothers are generally at an insufficient level.The proportion of vitamin D deficiency and deficiency of exclusive breast-fed infants is 58.3%,and that of lactating mothers is 85.4%.There was a positive and weak correlation between vitamin D level and vitamin D level.2.Higher serum 25-(OH)D levels were found in postnatal vitamin D supplements,daily outdoor activities for more than 2 hours,maternal vitamin D and calcium supplements during pregnancy and lactation,and exclusive breastfeeding babies born in spring.3.Vitamin D supplementation after birth and vitamin D and calcium supplementation during pregnancy and lactation are protective factors for normal vitamin D levels in exclusively breastfed infants,and winter birth is a risk factor for low vitamin D levels.4.The serum 25-(OH)D level of mothers with vitamin D and calcium supplementation during pregnancy and lactation and the average daily milk intake ≥250ml during lactation was higher.Supplementation of vitamin D and calcium during lactation is the protective factor of normal vitamin D level.