Employment in electronics manufacturing and risk of spontaneous abortion

A large case-control study of environmental risk factors for spontaneous abortion was conducted among women living in Santa Clara County, California. Because of the prevalence of electronics production work within this population, a specialized questionnaire was administered to women who self-identified as electronics production workers. Spontaneous abortions were identified from pathology records, and controls were identified from birth certificates. The odds ratio for spontaneous abortion and any electronics production work was 0.94 (95% confidence interval = 0.58, 1.5). Odds ratios for the three main branches of electronics production (semiconductor fabrication, printed circuit board manufacturing, and assembly) were likewise near or below unity. Specific production activities with elevated odds ratios included semiconductor diffusion, parts encapsulation, soldering, and flux removal, although the numbers were small and none of the confidence intervals excluded unity. Limitations of this study included modest statistical power and a potential for nondifferential misclassification of exposures, both of which could bias findings toward the null.