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

In Chinese women receiving IVF/ICSI-ET, the serum level of 25(OH)D demonstrated a nonlinear positive correlation with pregnancy outcomes (CPR and LBR), with stronger correlations above 25 ng/ml and worse yields below 30 ng/ml. However, it could not yet be considered different in distinct ages.