Risk factors for low birthweight in New Zealand, 1981-83

This paper describes the patterns of risk factors for low birthweight in a cohort of New Zealand births. The trend of low birthweight with maternal age and parity was U-shaped. Maori mothers had the highest (79.38/1000 livebirths) and Pacific Island mothers the lowest (39.88/1000), rates of low birthweight infants. There was an indication that the risk for Pacific Island mothers was modified by the mother's place of birth. Compared to nonMaori nonPacific Island New Zealand born women, the risk was high for Pacific Island New Zealand born women (RR = 1.27, 95% CI 1.04-1.56), but low for nonNew Zealand born Pacific Island mothers (RR = 0.70, 95% CI 0.61-0.79). The risk for Maori mothers increased if the father was also of Maori ethnic origin. The risk of a low birthweight infant increased (p less than 0.001) with social class, and the rate was high among exnuptial births (75.25/1000 live births). The rates of low birthweight for nonMaori and Pacific Island births in the South Island were similar to those in the North Island, but among Maori births the rate in the South Island (RR = 0.64, 95% CI 0.51-0.82) was lower than in the North Island.