EPIDEMIOLOGIC METHODS FOR PROSPECTIVE ASSESSMENT OF MENSTRUAL-CYCLE AND REPRODUCTIVE CHARACTERISTICS IN FEMALE SEMICONDUCTOR WORKERS

Methods were developed to assess potential adverse effects of semicond uctor fabrication work in a prospective study of reproductive health. All women aged 18-44 years who worked in seven silicon-wafer fabricati on sites in five companies and a frequency-matched sample of women in nonfabrication jobs were included. Among 3,480 selected for screening, 2,639 (75%) completed a self-administered questionnaire to identify w omen at risk of pregnancy. Among the 739 (28%) eligible women, 481 (65 %) completed baseline interviews and 402 (83.6%) completed at least on e menstrual cycle of follow-up by providing daily diaries and daily ur ine samples. Menstrual cycle characteristics were assessed from questi onnaires and diaries. Urine samples were assayed for reproductive horm ones to identify conceptions. The usual cycle length recalled at basel ine was 28 days. The mean cycle length (MCL) recorded in diaries was 2 9 days, with greater dispersion than at baseline. The median of the MC L from diary data was 28 days for women reporting regular cycles at ba seline but 34 days for women reporting irregular cycles at baseline, a nd the median standard deviation in cycle length per woman was 2.5 day s and 7.5 days, respectively. The prospective method, while expensive and labor intensive, showed good compliance. Nevertheless, recall also provided reasonably accurate estimates and distinguished women with r egular and irregular cycles. (C) 1995 Wiley-Liss, Inc.