Polycyclic aromatic hydrocarbons exposure as a potential risk factor for miscarriage among women in the United States: A secondary dataset analysis of NHANES data for the period 2005-2014.

Introduction: Numerous studies have shown that polycyclic aromatic hydrocarbons (PAHs) are endocrine disruptors associated with reproduction, with tobacco smoke identified as a major non-occupational source of PAH exposure. However, there is still a lack of information on the relationship between PAH exposure - particularly from tobacco-related sources - and miscarriage.

Methods: The data for this study were obtained from the National Health and Nutrition Examination Survey (NHANES) 2005-2014. Excluding populations with missing PAH, miscarriage, or baseline information, a total of 2573 individuals were included in this study. Logistic regression, linear regression, restricted cubic spline (RCS) analysis and subgroup analysis were used to analyze the effects of PAHs.

Results: Following logistic and linear regression analyses, we found that higher concentrations of 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxypyrene were associated with miscarriage (p<0.05, OR>1). Moreover, after RCS, we found a nonlinear relationship between 1-hydroxynaphthalene and miscarriage (p=0.01). The relationship between 1-hydroxynaphthalene and miscarriage could be described as an 'n-shaped' curve, with a cutoff value (4705 ng/L). At concentrations lower than the cutoff, there was a positive correlation between 1-hydroxynaphthalene and miscarriage. Conversely, at concentrations higher than the cutoff, there was a negative correlation between the two variables. Finally, a subgroup analysis was performed to explore the interaction effect of confounders with the outcome variables, to further demonstrate the robustness of the results.

Conclusions: The probability of miscarriage increases with increasing concentration of certain PAHs in the body. Enhancing monitoring of tobacco-related PAHs exposure is highly important for the prevention of miscarriage.