Association between heavy metals exposure and infertility among American women aged 20-44 years: A cross-sectional analysis from 2013 to 2018 NHANES data Original paper

What was studied?

This original research article investigated the association between exposure to heavy metals, specifically cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As), and female infertility in a representative sample of American women. Using data from three cycles of the National Health and Nutrition Examination Survey (NHANES, 2013–2018), the study measured blood and urinary levels of these metals and examined their correlation with self-reported infertility. The primary aim was to clarify whether elevated levels of these toxic metals are linked to increased risk of infertility, adjusting for relevant demographic and health covariates.

Who was studied?

The study population consisted of 838 American women aged 20–44 years, selected from NHANES 2013–2018 cycles based on availability of laboratory and questionnaire data. Women with a history of hysterectomy, bilateral oophorectomy, or incomplete data were excluded. Infertility was defined via self-report, using the question: “Have you ever attempted to become pregnant for at least a year, without becoming pregnant?” The cohort was diverse in terms of ethnicity, education, and marital status, with significant differences in age and BMI between infertile and control women.

Most important findings

The study found that urinary arsenic (As) and cadmium (Cd) levels were significantly higher in infertile women compared to controls. After controlling for several covariates, including age, ethnicity, education, marital status, poverty index ratio, BMI, regular menstrual periods, pelvic infection, and smoking history, urinary arsenic remained significantly associated with infertility. Women with higher urinary As levels had a substantially increased risk of infertility. Urinary Cd was also associated with infertility in less-adjusted models, but this association weakened with full adjustment. Blood and urinary Pb levels were not associated with infertility overall, but stratified analyses revealed that both blood and urinary Pb were positively correlated with infertility in women aged 35–44 and in those with BMI ≥25, highlighting age and obesity as effect modifiers. Blood Hg was not significantly associated with infertility in any model.

Key implications

This study highlights the potential reproductive health risks posed by environmental exposure to heavy metals among women of reproductive age. The robust association between urinary arsenic and infertility suggests that arsenic exposure (likely from contaminated water or certain foods) may disrupt female reproductive function, potentially through oxidative stress and endocrine disruption. The findings also indicate that older and overweight/obese women may be more susceptible to the adverse reproductive effects of lead. From a clinical and public health perspective, these results support the need for routine monitoring of heavy metals in at-risk populations and for interventions aimed at reducing environmental exposures, especially in vulnerable subgroups. The study also highlights the value of using urine measurements to assess chronic exposure, as opposed to blood levels that may reflect only recent exposure.