A prospective study examined the reproductive outcome, live birth, miscarriage or 9 months infertility, in 585 participating couples. Examination of the data relating to environmental and occupational exposure to chemicals and radiation revealed the following associations. Infertility was significantly associated with male factors of age, occupational exposure to dusts and occupation of labourer in men aged 35 or older. Female factors associated with infertility were age and home renovating if aged 35 or older. First trimester spontaneous miscarriage was associated with male factors of age, X-rays of the abdomen or back, occupation as a tradesperson, home exposure to glues, oil paints or oven cleaners. Female factors included age, visiting factories in the course of work, X-rays of the abdomen, home use of glues and working at home if aged less than 35. The most significant findings of the study are the poor outcomes associated with abdominal/back X-rays and home exposure to chemicals. The possible effects of having different numbers of positive factors was examined for each of miscarriage and 9 months infertility. Nine factors were examined for miscarriage and couples were found to have from zero to seven of these. The observed rate of pregnancy loss ranged from 3.7% to 75% with increasing numbers of factors. For infertility, four factors were examined and couples were found to have from zero to four of these. The observed rate of 'infertility' ranged from 8.4% to 33.3% with increasing numbers of factors. The statistical significance of both sets of results is p = < 0.0001. The effects of these exposures on outcome is thus cumulative.