The effect of serum vitamin D levels in couples on embryo development and clinical outcomes

Abstract Research Question The aim of the study was to explore whether serum vitamin D levels in men and women undergoing IVF/ICSI exerted an effect on embryo development and clinical outcomes. Design Between March 2016 and March 2017, we conducted a large retrospective observational cohort study and measured plasma 25-OHD levels prior to controlled ovarian stimulation in couples who had underwent IVF/ICSI (including 1883 women and 1720 men). Results Women were devided into four groups in terms of serum 25-OHD quartiles: 24.7 ng/ml(Q4). Statistically significant differences in top-quality embryo rates were found among different groups on Day3(P=0.016) but not on Day2(P=0.178) and Day5/6(P=0.452). Specifically, the top-quality embryo rate on Day3 was highest in Q2, with difference being statistically significant as compared to Q3(P=0.014). The linear regression showed that serum 25-OHD levels in women were not significantly related to top-quality embryo rates on Day2, Day3, Day5/6(P>0.05).There existed no differences in implantation rates, clinical pregnancy rates, abortion rates and live birth rates among groups(P=0.797,P=0.505,P=0.179, P=0.486). Logistic regressionrevealed that there was no significant difference among the groups inthe success of clinical pregnancy.In men,no significant association was found between vitamin D status and embryo development or clinical outcomes . Conclusions Vitamin D levels, in neither men nor women, was associated with embryo development in cleavage (Day2 and Day3) and blastocyst (Day5/6) stage and clinical outcomes. The possible reason might be that the threshold of vitamin D affecting reproductive process is relatively low, which requires a multicenter study at high latitudes region.