Background: Indoor air pollution (IAP) exposure and psychological status have been recognized as important risk factors for adverse pregnancy outcomes, but their mediating effects on recurrent spontaneous abortion (RSA) have not been analyzed. Therefore, the purpose of this study is to explore the association between IAP and RSA and to examine the mediating effect of psychological status on their association.
Methods: This study included 830 RSA cases and 2156 controls in Gansu province, China. The Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) questionnaires were used to collect information on participants' psychological status. The IAP exposure was collected by the survey on cooking fuel use, kitchen ventilation characteristics, cooking styles, and indoor smoking, etc. Multivariable logistic regression was used to examine the associations between IAP exposure and RSA. The mediation analysis was used to evaluate the mediation effects of IAP and psychological status on RSA while controlling for confounding.
Results: Among these cases, 16.87% cooked with unclean cooking fuel (UCF) and 37.00% lacked cooking ventilation, which was much higher than the controls. Active smoking and the use of UCF were associated with RSA, with an odds ratio (OR) of 3.374 [95% confidence interval (CI): 1.510-7.541] and 1.822 (95% CI: 1.328-2.500), respectively. We found that the use of a range hood was a protective factor for RSA, with an OR of 0.590 (95% CI: 0.463-0.752). There was a significant mediation effect of depression on the association between IAP and RSA, which accounted for 5.61%-9.22% of the total effect of IAP on RSA.
Conclusion: The IAP may be an important risk factor for RSA, which may be intensified by the poor psychological status, and the use of ventilation equipment when cooking is a protective factor for RSA.
Keywords: Cooking environment; Mediation effect; Psychological status; Recurrent spontaneous abortion; Smoking.
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