| Objective To describe maternal vitamin D level during 21 to 24 weeks and analyse its determinants.To explore the association of vitamin D levels of second trimester with fasting blood glucose of second trimester and the risk of gestational diabetes mellitus?GDM?.Methods Pregnant women cohort from Hefei First People's Hospital was established since Mar.2015 to Jun.2017.2 206 voluntary participants who took regular obstetric examination in the same hospital finished a questionnaire during 21to 24 weeks.At the same time,venous blood samples were collected for measuring fasting blood glucose and the serum 25?OH?D concentration.Follow up to obtain the diagnosis of GDM till delivery.Pregnant women with diabetes before conception,severe pregnancy complications?e.g.,cardiac dysfunction,severe anemia,gestational hypertensive?,assisted reproduction,multiple gestation,uncomplete information of follow-up during pregnancy and lost to follow-up were excluded from the study.Finally,we collected 2 206 pregnant women's biological samples and complete health information including maternal social demographic characteristics,basic lifestyle,health condition before and during pregnancy,vitamin D supplementation before and during pregnancy.The factors which influencing fasting food glucose and25?OH?D of second trimester were anslysed by using trend line chi-square test and linear regression.Multi-factor linear regression model and nonlinear fitting model were applied to examined the differences of fasting food glucose in second trimester among 25?OH?D quintiles.Multi-factor logistic regression model was applied to explore the relation between 25?OH?D and GDM.Results The mean of maternal fasting food glucose at second trimester was?4.68±0.44?mmol/L.The mean of maternal 25?OH?D at second trimester was?39.76±16.06?nmol/L.The factor influencing fasting food glucose at second trimester were pregnant age,BMI before pregnancy,weight gain per week during pr egnancy,charity,parent's diabetes history,season of blood sampling,husband drinking and smoking,oral cod liver oil more than 2 times per week during first trimester.The factor influcing 25?OH?D at second trimester were BMI before pregnancy,weight gain per week during pregnancy,family income lower than 6 001 RMB,season of blood sampling,charity,less outdoor time,less sunlight exposure,calcium and cod liver oil more than 2 times per week during first trimester,cod liver oil,multi-vitamin,calcium and milk more than 2 times in recent week.The relation between 25?OH?D and fasting food glucose at second trimester was nonlinear:when 25?OH?D at second trimester lower than 50nmol/L,there was no significant relation between 25?OH?D and fasting food glucose?r=-0.025,P=0.307?;when 25?OH?D at second trimester more than 49.9nmol/L,there was significantly negative relation between 25?OH?D and fasting food glucose?r=-0.14,P=0.002?;Vitamin D deficiency rate at second trimester was 76.7%?1692/2206?.With the increase of 25?OH?D quintiles,the prevalence of GDM decreased significantly(?2trend=33.85,P<0.001).Comparing to the first quintile,the prevalence of GDM decreased significantly in the fourth?RR=0.66,95%CI:0.470.93,P=0.018?and fifth quintile?RR=0.34,95%CI:0.230.51,P<0.001?respectively.Comparing to vitamin D undeficiency group??50nmol/L?,the adjusted RR value of GDM prevalence were respectively 2.04?95%CI:1.482.80,P<0.001?and 2.56?95%CI:1.794.65,P<0.001?in vitamin D mild deficiency group?3050nmol/L?and severe deficiency group?<30nmol/L?.Conclusions The relation between vitmamin D and fasting food glucose at second trimester was nonlinear.Only if vitamin D at second trimester higher than or equal to50nmol/L,it had negative relation with fasting food glucose and the prevalence of GDM.This enlightened us that vitamin D supplementation may improve maternal glucose status and then prevent GDM effectively only if it achieved“both enough”which meaned the supplementation dose was enough and maternal 25?OH?D elevated to enough concentration. |
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