To test the hypothesis that children born to mothers living near the sea are at increased risk of limb reduction defects. Descriptive data analysis. The northern health region of England. All children born between 1 January 1985 and 31 December 1992 in the northern region of England with isolated limb reduction defects. The birth prevalence of isolated limb reduction defects was not affected by the distance the mother lived from the sea. There was some evidence of space-time clustering, but there was no evidence of statistically significant variation in the occurrence of the condition with sex, time of birth (monthly or yearly), or county of birth. There is no evidence that children born to mothers living near the sea are at increased risk of limb reduction defects.