7949 male doctors in the U.K. were surveyed to determine whether there was a relation between operating-theatre work (exposure) and abnormalities in the obstetric history of their marriages. Paternal exposure did not appear to influence the overall abortion-rate or the frequency of major congenital abnormality and involuntary infertility. The frequency of minor congenital abnormality in the children of exposed fathers was 3.09% compared with 2.35% (non-exposed). Maternal exposure was associated with a 15.5% frequency of abortion. Matching of exposed and non-exposed pregnancies with respect to birth order, maternal age, and smoking-habits suggests that the risk of abortion may increase by 158% to 271% with maternal exposure.