Background: Although Torres Strait Islanders (TSIs) are often combined with Aborigines, they are a distinct group and would prefer to be considered separately. The Queensland Perinatal Data Collection (QPDC) has been the only population-based, perinatal collection in Australia that has distinguished between Aboriginal and TSI mothers. It provided a unique opportunity to compare outcome measures based on birthweight in the TSI, Aboriginal and white populations. TSIs were of particular interest because recent research from overseas suggests that in groups with high rates of obesity and diabetes, birthweight is not a valid outcome measure. This is of concern because outcome measures based on birthweight have been proposed as a way of monitoring the neonatal health of Indigenous Australians.

Methods: Retrospective analysis of 10 years of routine data from the QPDC.

Results: TSIs had a birthweight distribution similar to that of whites, but mortality rates similar to those of Aborigines. For birthweights between 2500g and 4000g, TSIs had mortality rates that were 2.5 times higher than those for whites (95%Cl: 1.3 to 4.2).

Conclusions: Although birthweight is widely used, it is not necessarily a valid outcome measure in all populations. For TSIs, maternal conditions such as obesity and diabetes might cause changes in the uterine environment that produce heavier, but not healthier babies.