Video display terminal use and spontaneous abortion risk

A matched case-control study investigated the potential effects of video display terminal (VDT) use on risk of spontaneous abortion in pregnancy. Structured interviews were administered to 334 cases immediately following a miscarriage. For each case, two age and parity-matched controls were enrolled, the first being a woman still pregnant (less than 25 weeks' gestation), and the second a woman in the postpartum ward of the same participating hospital. Separate analyses were carried out for each comparison group due to potential and observed differences in recall loss and selection bias. The overall exposure to VDT's during the period of interest (three months preceding the last menstrual period [LMP] to four months post-LMP) did not indicate an increased risk for either control group comparison (OR = 1.14, p = 0.47 with postnatal controls; OR = 0.80, p = 0.20 with prenatal controls). Furthermore, when exposure data were re-classified to remove women with distant or single exposures, no significant odds ratios were found. While several socioeconomic and obstetric variables were significantly associated with VDT use, multivariate analysis did not alter the lack of association of VDT use with case-control status. Finally, evidence for recall bias in postnatal control reporting, evidenced by underreporting of trivial exposures in this group, is examined.