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.

Inclusion Criteria:

• female with only fallopian tube factor or male factor infertility,first IVF/ICSI cycle,18 years old≤age≤35 years old,take a long protocol or super-long protocol,18≤BMI≤25, menstrual regularity(periodic change < 7 days)

Exclusion Criteria:

• Hyperprolactinemia, Thyroid dysfunction, uterine malformation ( inadequacy mediastinal uterus ≥1.0cm, Unicornate uterus, double uterus, T Angle of uterus, etc.), uterus adhesion, untreated hydrosalpinx , hysteromyoma（ hysteromyoma≥2.0 cm, and/or Uterine fibroids located within the endometrium≤1cm), endometriosis, diabetes, hypertension, adrenal cortex hyperplasia, Cushing's syndrome, a pituitary amenorrhea

the study population will be selected from patients of Reproductive and Genetic Hospital of CITIC-Xiangya