Effects of Vitamin D Status on the Outcome of Ivf - Embryo Transfer

At present, there is no agreement on the effect of vitamin D level in serum and follicular fluid on the outcome of IVF-ET pregnancy. Most of these studies were based on the research of total 25 (OH) D, which have ignored that the biological activity of vitamin D molecule is not total 25 (OH) D, but free vitamin D or vitamin D bioavailable, and have flaws in methodology. This project intends to make a prospective cohort study with large sample, based on a complete methodology of total vitamin D and free vitamin D to measure maternal vitamin D levels in blood,to systematically study the effect of maternal vitamin D status on IVF - ET pregnancy outcome. This study is also the first to study the relationship between maternal vitamin D status and the outcome of IVF-ET pregnancy using a complete methodology.