Does vitamin D level associate with pregnancy outcomes in Chinese women undergoing in vitro fertilization/intracytoplasmic sperm injection‐embryo transfer? A retrospective cohort study

Aim To explore the relationship between serum 25(OH)D level and pregnancy outcomes (clinical pregnancy rate [CPR] and live birth rate [LBR]) in Chinese women receiving in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI)‐embryo transfer (ET) (IVF/ICSI‐ET). Methods A total of 612 patients included in the study were divided into four cohorts according to serum 25(OH)D with the threshold of 20 ng/ml, 25 ng/ml, 30 ng/ml, and retrospectively analyzed. Results None of the baseline characteristics of participants was significantly different in the four cohorts except gravid status. The trend of 25(OH)D concentration was positively correlated with CPR and LBR. The younger (age: p