JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):171
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263917

P-159. Methylmercury exposure and its impact on female fertility: A systematic review

Catarina Favero Monteiro¹, Gabriel Monteiro¹, Julia Roverso Correa Silveira¹

¹ Universidade Santo Amaro - São Paulo - SP - Brasil

Objective: Growing evidence suggests that methylmercury (MeHg), a widespread environmental contaminant, can adversely affect female reproductive and endocrine function. This review aims to synthesize current findings on MeHg exposure and its implications for fertility in women of reproductive age.
Methods: A systematic review was conducted using the PubMed, Web of Science, and SciELO databases, covering studies published between 2000 and 2025. The search strategy included the terms "mercury," "methylmercury," "MeHg," "female fertility," "reproductive health," and "endocrine disruption." From an initial pool of 121 articles, we excluded studies that focused exclusively on elemental or inorganic mercury, as well as those addressing only male fertility. After applying these criteria, 15 articles were selected for full-text analysis.
Results: Omega-3 fatty acids support female reproductive health and are primarily obtained through fatty fish such as salmon, tuna, sardines, and whitefish. While current guidelines recommend two to three servings per week, these fish may also contain methylmercury (MeHg), a toxic compound that bioaccumulates in the food chain. The impact of mercury on female reproduction has been recognized since 1829, with early reports describing symptoms such as amenorrhea, menorrhagia, and miscarriage. More recently, MeHg exposure has been associated with endocrine disruption and reproductive toxicity, including impaired oocyte quality, altered follicular development, and hormonal dysregulation. Currently, fish and shellfish consumption represent the main source of non-occupational MeHg exposure. In a study involving 150 women aged 16 to 45, 38% presented hair mercury levels above the safety threshold, with higher levels correlating with fish intake and a history of infertility. Mercury exposure has also been linked to menstrual irregularities, hormonal imbalances, and an increased risk of adverse reproductive outcomes. Mechanistically, MeHg acts as an endocrine disruptor by mimicking or blocking hormone receptors and inhibiting enzymes involved in hormone synthesis. It alters the progesterone-to-estrogen ratio and suppresses LH and FSH secretion, potentially impairing follicular development and ovulation. Evidence from case– control studies further supports the association between MeHg exposure and infertility. One study comparing 157 infertile couples undergoing IVF with 26 fertile couples without occupational mercury exposure found elevated blood mercury levels in the infertile group, with seafood intake contributing to the increase. Another case–control study involving 98 infertile women and 43 controls also reported significantly higher mercury levels among the infertile participants. A prospective cohort study demonstrated that higher hair mercury concentrations were associated with a diminished ovarian response to gonadotrophin therapy, as evidenced by lower oocyte yield and fewer developing follicles in women undergoing IVF treatment. Furthermore, another study identified an inverse association between hair mercury levels and the probability of obtaining mature oocytes during IVF treatment, suggesting that mercury exposure may impair oocyte maturation. Additionally, a study assessing hair mercury concentrations in 30 subfertile women following ovarian stimulation found that mercury exposure was linked to disrupted ovarian function. Collectively, these findings reinforce the hypothesis that MeHg negatively impacts female reproductive health and underscore the importance of evaluating environmental mercury exposure in fertility assessments.
Conclusion: Methylmercury (MeHg) exposure represents a widespread health risk primarily linked to the consumption of certain fish species and remains a significant public health concern. This review consolidates evidence associating elevated MeHg levels with detrimental effects on female reproductive health, including hormonal imbalances, impaired follicular development, reduced oocyte quality, and unexplained infertility. These findings highlight the urgent need for public health strategies that promote safer dietary practices, especially the selection of low-mercury fish species, as well as comprehensive efforts to mitigate environmental mercury contamination.