HISTORICAL COHORT INVESTIGATION OF SPONTANEOUS-ABORTION IN THE SEMICONDUCTOR HEALTH STUDY - EPIDEMIOLOGIC METHODS AND ANALYSES OF RISK IN FABRICATION OVERALL AND IN FABRICATION WORK GROUPS

The risk of spontaneous abortion (SAB) in the semiconductor industry w as examined in a historical cohort study of pregnancies at 14 companie s. We identified female employees who had worked for at least 6 months and whose ages ranged from 18 to 44 years during the 1986-1989 study period. Using company records, we included all fabrication-room (fab) employees and an approximately equal number of nonfabrication (nonfab) employees, for a total sample of 7,269. Telephone interviews with 6,0 88 women (84%) identified 904 eligible pregnancies and 113 SABs. Expos ure classification was based on questionnaire and industrial hygiene a ssessments of tasks the women performed during the first trimester of pregnancy. Using logistic regression to control for age, smoking, ethn icity, education, income, year of pregnancy, and stress, we found a hi gher risk of SAB in fab employees than in nonfab employees (15.0% of f ab pregnancies ended in SAB vs. 10.4% of nonfab pregnancies, adjusted relative risk [RR] = 1.43, 95% CI = 0.95-2.09). Analysis of fab work g roups showed that the highest relative risk was in masking employees ( 17.5% SAB rate, adjusted RR = 1.78, 95% CI = 1.17-2.62 in comparison w ith nonfab employees). Within masking, the highest risk was found in e tching-related process employees (22.2% SAB rate, adjusted RR = 2.08, 95% CI = 1.27-3.19 in comparison to nonfab employees). (C) 1995 Wiley- Liss, Inc.