Vitamin D levels in couples undergoing in vitro fertilization treatment: lack of association with embryo quality or pregnancy rates

ObjectiveTo investigate the potential impact of vitamin D (VD) serum levels on couples going through in vitro fertilization treatment in terms of embryo quality and pregnancy rates.DesignA retrospective cohort study.SettingA private human reproduction center.Patient(s)A total of 267 couples underwent intracytoplasmic sperm injections between January 2017 and March 2019.Intervention(s)The couples were categorized into four groups on the basis of 25-hydroxy VD (25OHD) levels measured at the beginning of the stimulation protocol: group 1 with 25OHD levels ≥30 ng/mL for both women and men; group 2 with 25OHD levels <30 ng/mL for both; group 3 women with 25OHD levels <30 ng/mL and men with 25OHD levels ≥30 ng/mL; and group 4 with women with 25OHD level ≥30 ng/mL and men with 25OHD level <30 ng/mL.Main Outcome Measure(s)We consider the quantity and quality of embryos during the cleavage as well as blastocyst stages as primary outcomes. Correspondingly, the clinical pregnancy rate (CPR) was regarded as a secondary outcome.Result(s)Our findings revealed no significant correlations between the studied VD groups and the evaluated outcomes. This includes the quantity and quality of embryos during the cleavage and blastocyst stages, as well as the CPR. Primary analysis revealed a small but statistically significant difference in the duration of controlled ovarian stimulation between group 1 and group 2 (95% confidence interval, 0.07–3.04) and between group 1 and group 3 (95% confidence interval, 0.05–3.23).Conclusion(s)The present study found no correlation between the studied VD levels and the quantity as well as quality of cleavage or blastocyst stage embryos, nor did it show any impact on CPRs. Further well-designed, prospective studies are warranted to determine whether and how vitamin D affects reproductive outcomes.