BACKGROUND: It is estimated that 10-15% of all couples have experienced an infertility problem. The objective of this study was to evaluate the effect of occupation on the time interval between when a couple starts unprotected intercourse and a clinically recognizable pregnancy time to pregnancy (TTP). METHODS: Data from 622 women who successfully delivered in the week preceding the interview were analysed using the Cox proportional hazards regression. Thirty independent variables were included in the full model. RESULTS: Eleven per cent of women had to wait more than one year before conceiving (mean TTP = 6.7 months). The regression analysis showed that the most important determinants of TTP are the age of the woman (rate ratio = 0.44 for age 35+) and her parity (rate ratio = 1.39). TTP also increased significantly with maternal smoking (rate ratio = 0.77), and decreased with coital frequency (rate ratio = 1.24 for > or = 6 per month) and consumption of coffee (rate ratio = 1.29). None of the female occupational exposures has been found to have an independent statistically significant effect, while male occupation in industry and exposure to welding fumes were associated with an increase of TTP (rate ratio = 0.73 and 0.78, respectively). CONCLUSIONS: Female occupational exposures seem to have only a small effect on TTP compared with biological and lifestyle factors. The present data also suggest that work-related factors may have a bigger influence on male fecundity.
BACKGROUND: It is estimated that 10-15% of all couples have experienced an infertility problem. The objective of this study was to evaluate the effect of occupation on the time interval between when a couple starts unprotected intercourse and a clinically recognizable pregnancy time to pregnancy (TTP). METHODS: Data from 622 women who successfully delivered in the week preceding the interview were analysed using the Cox proportional hazards regression. Thirty independent variables were included in the full model. RESULTS: Eleven per cent of women had to wait more than one year before conceiving (mean TTP = 6.7 months). The regression analysis showed that the most important determinants of TTP are the age of the woman (rate ratio = 0.44 for age 35+) and her parity (rate ratio = 1.39). TTP also increased significantly with maternal smoking (rate ratio = 0.77), and decreased with coital frequency (rate ratio = 1.24 for > or = 6 per month) and consumption of coffee (rate ratio = 1.29). None of the female occupational exposures has been found to have an independent statistically significant effect, while male occupation in industry and exposure to welding fumes were associated with an increase of TTP (rate ratio = 0.73 and 0.78, respectively). CONCLUSIONS: Female occupational exposures seem to have only a small effect on TTP compared with biological and lifestyle factors. The present data also suggest that work-related factors may have a bigger influence on male fecundity.
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