Banks N, Sun F, Krawetz SA, et al. - Researchers conducted a secondary analysis of a randomized, controlled trial with the aim to determine the correlation between vitamin D levels in the male partner and fertility outcomes in couples with mild male factor infertility. From nine fertility centers in the United States, they identified 154 men (n = 154) with sperm concentration between 5 and 15 million/mL, motility ≤ 40%, or normal morphology ≤ 4% as eligible. These men were randomly assigned to receive a vitamin formulation including vitamin D 2,000 IU daily or placebo for up to 6 months. Findings did not suggest any significant impact of vitamin D deficiency in the male partner on semen parameters or treatment outcomes.