Fecundity and the use of video display terminals.

The association between prolonged waiting time to pregnancy and the use of a video display terminal (VDT) was investigated among commercial and clerical employees in Denmark. Information on 24,352 pregnancies was obtained through register linkage with two national registers. A random sample of 2252 pregnancies was drawn, and the women were asked for information on waiting time to pregnancy, occupational exposures, and life-style factors. The overall exposure to a VDT indicated a slightly increased association with prolonged waiting time to pregnancy. The relative risks for waiting more than one year were 1.23, 0.77, and 1.61 for the women who worked with a VDT for 1-10, 11-20, and > or = 21 h per week, respectively. Only the last relative risk was statistically significant. The results could be explained by methodological shortcomings such as recall bias or confounding by alternative factors that might affect time to pregnancy, or simply by the lack of statistical power.