Preconception vitamin D level and In Vitro Fertilization- pregnancy outcome.

OBJECTIVES: Vitamin D deficiency impairs female fertility and the success of in vitro fertilization (IVF). The recommended serum 25-hydroxy vitamin D (25(OH)D) level in IVF-conceived pregnancies is still debated. We aimed to explore the relationship of preconception serum 25(OH)D level with pregnancy outcome following IVF treatment. We also explored the utility of the currently recommended serum 25(OH)D cut-off of ≥50 nmol/L for women undergoing IVF therapy.

METHODS: Retrospective cohort of women who had undergone IVF therapy. Of the women who started IVF therapy (n=354), 218 completed the study. This comprised two groups, successful pregnancy (pregnant group, n=160) and those who did not achieve a successful pregnancy (non-pregnant group, n=58). Preconception serum samples were analyzed for reproductive hormones, fasting glucose, insulin and 25(OH)D levels.

RESULTS: Overall, median (IQR) age was 32(6) years, BMI 25.7(7.4) kg/m2 and HbA1c 5.2(0.6)%. 25(OH)D level was significantly higher at preconception in the pregnant group (56.4(21.4) vs 47.9(29.16) for non-pregnant; p=0.001). Preconception 25(OH)D level was a significant predictor of IVF outcome (B=0.04; 95% CI: 1.01, 1.06; p=0.001), with greater IVF success associated with a serum 25(OH)D level ≥50 nmol/L (OR: 0.46; p=0.01).

CONCLUSIONS: Preconception 25(OH)D sufficiency (≥50 nmol/L) associates with successful pregnancy outcome following IVF therapy.