Evidence check: Vitamin D 25-OH in the context of fertility

Vitamin D (25-OH) is increasingly discussed in the context of fertility. Observational studies suggest that low vitamin D levels are associated with reduced ovarian reserve, lower live birth rates after IVF, and poorer sperm quality in men. Mechanistically, vitamin D receptors are expressed in reproductive tissues and may influence hormone regulation and immune function. However, interventional trials show mixed results: some randomized controlled trials (RCTs) report improved pregnancy rates with supplementation, while others find no significant benefit. The evidence is therefore moderate – plausible biological pathways exist, but clinical utility remains uncertain. Correcting a deficiency is still advisable for overall health, but vitamin D testing alone is not a fertility solution. MyBody-X offers 25-OH measurement, but results should be integrated into a comprehensive fertility workup. Consumers should be cautious about overinterpreting single biomarkers.