Influencing Factors Of Vitamin D Level And Connection With Gestational Diabetes Mellitus In Pregnant Women

Objective:To investigate the current status of serum 25-hydroxyvitamin D[25(OH)D]levels in pregnant women in the first and second trimester in Huaibei area,to analyze the influencing factors of serum 25(OH)D deficiency.To investigate the association between serum 25(OH)D levels in different trimesters and the incidence of Gestational Diabetes Mellitus(GDM).Methods:The participants in this study were recruited from the follow-up subjects of An Hui Huaibei Birth Cohort(A-HBBC)since November 2020.Pregnant women were included in the cohort when they participated in A questionnaire survey in the first trimester(<14 weeks of pregnancy),and early serum samples were collected on the same day.The questionnaire consisted of four parts:socio-demographic information,pregnancy characteristics,dietary habits and nutritional supplements,sleep and anxiety status.At the second trimester of pregnancy(24-28 weeks),a questionnaire survey was conducted and serum samples were collected on the same day.The Oral Glucose Tolerance Test(OGTT)data of pregnant women were obtained from the maternal health manual.In this study,59 GDM patients were diagnosed as a case group,and were paired with the pregnant woman’s age and pre-pregnancy BMI,and selected 236healthy pregnant women as a control group.Serum 25(OH)D level was measured by electrochemiluminescence.IBM SPSS 23.0 statistical software was used to analyze the data.The influencing factors of serum 25(OH)D deficiency in the first and second trimesters were analyzed by pearson chi-square test and Fisher’s exact probability method for univariate analysis,and binary Logistic regression analysis model for multivariate analysis.t test andχ~2 test were used for univariate analysis of the influencing factors of GDM,and Logistic regression analysis model was used to explore the effect of serum 25(OH)D level on the incidence of GDM.Results:A total of 885 healthy pregnant women in the first trimester were enrolled,and 517 women were followed up until the second trimester.The average age of pregnant women was 28.18±4.28 years(18-44 years),of which 69(7.8%)were≥35years old.The mean level of serum 25(OH)D in the first trimester of 885 pregnant women was 18.31±7.15ng/m L.The mean serum 25(OH)D level of 517 pregnant women was 23.06±7.52ng/m L.In the first trimester,there were 531 pregnant women with serum 25(OH)D<20ng/m L,and the deficiency rate was 60%.Only 42 pregnant women had serum 25(OH)D≥30ng/m L,and the sufficiency rate was 4.7%.In the second trimester,serum 25(OH)D level was less than 20ng/m L in 180 pregnant women,and the deficiency rate was 34.8%.There were 88 pregnant women with serum25(OH)D≥30ng/m L,and the sufficiency rate was 17.0%.The influencing factors of vitamin D level in early pregnancy are as follows:1.Compared with serum sampling in winter,serum sampling in summer(OR=0.157,95%CI:0.081-0.305)and autumn(OR=0.255,95%CI:0.141-0.460)could help to improve vitamin D levels in early pregnancy.2.Compared with pregnant women aged18-24 years,aged 25-29 years and 30-34 years had a significantly lower risk of early vitamin D deficiency,(OR=0.539,95%CI:0.317-0.918)and(OR=0.494,95%CI:0.273-0.893)respectively.3.Compared with those with a pre-pregnancy BMI<18.5,pregnant women with a pre-pregnancy BMI≥35 had an increased risk of vitamin D deficiency in the first trimester(OR=2.023,95%CI:1.70-3.11).4.Compared with those without eating disorders in the first trimester,those with eating disorders had an increased risk of vitamin D deficiency in the first trimester(OR=1.352,95%CI:1.019-1.794).5.Pregnant women who did not take VD supplements in the first trimester had a significantly increased risk of vitamin D deficiency(OR=2.333,95%CI:1.474-3.693).6.The risk of vitamin D deficiency in early pregnancy in pregnant women with longer waiting time before falling asleep is lower than that in those with waiting time less than15 minutes.7.Pregnant women with sleep duration≥8 hours had a higher risk of vitamin D deficiency than those with sleep duration<8 hours in the first trimester(OR=1.960,95%CI:1.276-3.010).The influencing factors of vitamin D level in second pregnancy are as follows:1.Compared with serum sampling in winter,serum sampling was more common in spring(OR=0.267,95%CI:0.121-0.591),summer(OR=0.153,95%CI:0.056-0.418)and autumn(OR=0.201,95%CI:0.082～0.492)Both are helpful to reduce the risk of vitamin D deficiency in pregnant women in the second trimester.2.Compared with pregnant women with passive smoking during pregnancy,never smoking(OR=0.474,95%CI:0.235-0.985)was associated with a reduced risk of vitamin D deficiency in the second trimester.3.Compared with pregnant women who took nutritional supplements in the second trimester,pregnant women who did not take calcium supplements in the second trimester(OR=1.965,95%CI:1.019-3.793)and did not take folic acid supplements in the second trimester(OR=2.191,95%CI:1.229-3.908)and no supplementation of VD in the second trimester(OR=2.208,95%CI:1.210-4.031)increased the risk of vitamin D deficiency.The incidence of GDM in this cohort was 12.04%(59/490).The levels of 1-h PBG,2-h PBG and 1h blood glucose elevation in vitamin D deficiency group were higher than those in non-deficiency group in early pregnancy,and the differences were statistically significant(P<0.05).After adjusting for age,pre-pregnancy BMI,weight gain in the second trimester,and VD supplementation,women with vitamin D deficiency in the first trimester had a higher risk of GDM than those without vitamin D deficiency(OR=1.998,95%CI:1.072-3.724).No significant association was observed between vitamin D deficiency and GDM.Conclusion:This study found that the serum 25(OH)D level and sufficiency rate of pregnant women in the first and second trimesters of pregnancy in Huaibei area were low,which were affected by multiple factors such as season,age,pre-pregnancy BMI,eating disorders,oil intake,VD nutritional supplements,and waiting time before falling asleep.Vitamin D level in the first trimester of pregnancy is associated with the risk of GDM.Vitamin D deficiency in the first trimester of pregnancy is associated with the increased risk of GDM.There is no significant association between vitamin D deficiency and GDM in the second trimester.