Body weight and 25-hidroxyvitamin D follicular levels: a prospective study of women submitted to in vitro fertilization

OBJECTIVE Vitamin D deficiency has been largely related to infertility in animals. However, data demonstrating a direct association between hypovitaminosis D and infertility in humans are still conflicting. Increased body weight and an elevated body mass index (BMI) are known for their association with infertility. Therefore, this study attempted to verify whether increases in body weight and the BMI were associated with lower 25-hidroxyvitamin D [25(OH)D3] levels in the follicular fluid (FF) of patients treated for infertility with intracytoplasmic sperm injections (ICSI). This study aimed to assess the FF levels of 25(OH)D3 in women submitted to ICSI and correlate these levels with the different body weight and BMI values observed in the enrolled cohort. METHODS The FF aspirates of 199 patients submitted to ICSI were collected after oocyte aspiration to check whether FF 25(OH)D3 levels were associated with weight regardless of the etiology of infertility. Chemiluminescent assays were used to assess FF 25(OH)D3 levels. The etiology of infertility was defined based on patient clinical history and follow-up. RESULTS The patients enrolled in the study were divided into three groups according to their FF 25(OH)D3 levels, as follows: a) deficient (n=71; <20 ng/ml); b) insufficient (n=64; 21< 25(OH) D3>29 ng/ml); and c) sufficient (n=56 >30ng/ml) levels. Patients with lower FF 25(OH)D3 levels had a greater mean weight (64.1kg) when compared to patients with higher 25(OH)D3 levels (60.7kg), p<0.01. No differences were observed in terms of age or etiology of infertility. CONCLUSION The body weight of the individuals with FF 25(OH)D3 deficiency measured in single follicles was significantly higher regardless of the etiology of infertility. Further epidemiologic and molecular studies are required to verify whether the amount of follicular 25(OH)D3 affects the outcome of IVF procedures.