A Scoping Review on Iodine Status and Fertility: Results From Human Studies

Recent studies have indicated that insufficient iodine availability may impair reproductive health, potentially contributing to reduced fertility. This scoping review compiled and analyzed findings from 26 human studies exploring the link between iodine status and fertility in both sexes. The research, published between January 1, 2000, and February 16, 2025, was sourced from databases including PubMed, Scopus, Embase, Web of Science, and the Cochrane Library. Iodine status was assessed using urinary iodine concentration, iodine-to-creatinine ratios, and dietary assessments via food-frequency questionnaires. In women, fertility indicators examined included time to conception, fecundability ratio, miscarriage rates, spontaneous abortions, and stillbirths. Available studies suggest that iodine deficiency prior to conception may hinder female fertility, although its influence on pregnancy outcomes, such as miscarriage or stillbirth, is less definitive. In men, the studies assessed semen parameters-such as volume, concentration, motility, morphology, and total sperm count-along with hormonal markers such as testosterone levels. The results show the importance of optimal iodine status, as both deficiency and excess may negatively affect male reproductive health. However, current research includes mixed findings regarding the effectiveness of iodine supplementation in improving fertility and pregnancy outcomes. In conclusion, this scoping review highlights that both insufficient and excessive iodine intake may adversely influence reproductive outcomes; however, the current body of evidence remains limited. Moreover, the potential benefits of iodine supplementation on conception-especially among women undergoing assisted reproductive technologies-are not yet well established and warrant further investigation.