BACKGROUNDBirth defects in infants born to non-Caucasian, non-Indigenous mothers in Australia have not been described in detail previously.METHODSUsing data from the Western Australian Maternal and Child Health Research Data Base, an index cohort of all non-Caucasian, non-Indigenous mothers giving birth in Western Australia between 1985 and 1995 (n = 17,706 births) was compared with a 10% random sample of births to Caucasian mothers (n = 24,180) over the same period.RESULTSOverall, the index mothers had a 21% less risk of having a baby with birth defects (prevalence ratio, 0.79; 95% confidence interval, 0.72–0.86). The six major countries of birth of the index mothers were Vietnam, the Philippines, Singapore, Malaysia, India, and New Zealand. Mothers from Vietnam and the Philippines were significantly less likely to have a baby with a birth defect. The prevalences for the remaining four maternal countries of birth were not significantly different from that in the comparison cohort.CONCLUSIONSThe difference in risk of birth defects is probably not a result of confounding by maternal age, plurality, parity, socioeconomic status, marital status, or place of residence. However, it may be a real difference or a result of ascertainment bias.