Abstract
            Introduction: There are controversies about relationship between serum and follicle vitamin D levels and in vitro fertilization (IVF)  outcomes.  
  Objectives: The goal of this study was to determine association between serum and follicular vitamin D levels and IVF outcome in the  Iranian population.  
  Patients and Methods: This cohort study was conducted in a women’s hospital. One hundred and sixty patients (mean age = 28 years )  who were candidates (by simple sampling) for IVF enrolled in the study. Levels of 25 (OH)-D in follicular fluid and serum were measured.  Biochemical pregnancy was determined by detecting serum β-hCG. A detectable gestational sac was considered as a characteristic of clinical  pregnancy.  
  Results: Biochemical pregnancy was detected in 49 (30.6) and clinical pregnancy in 39 (24.4). Mean vitamin D levels of serum and follicular  fluid were not significantly different between cases that had clinical pregnancy or not. In cases with serum vitamin D level less than 30, mean  follicular vitamin D level and body mass index (BMI) were significantly lower than the cases with serum vitamin D level more than 30. Mean  serum vitamin D levels, biochemical and clinical pregnancy rates were significantly different in cases with follicular vitamin D level less or  equal/more than 30. Logistic regression by considering biochemical pregnancy as dependent variable and other variables as independent  variables showed that the only independent predictor was grade of embryo  
  Conclusion: Follicular vitamin D level could affect pregnancy outcome in IVF cycles while serum vitamin D levels do not play any role in  the IVF outcome.