Ethnicity and birth outcome: New Zealand trends 1980-2001: Part 4. Pregnancy outcomes for European/other women

BACKGROUND: In the early 1980s European/other women made up 80% of New Zealand's population and experienced rates of preterm birth that were lower than for other ethnic groups. Rates of small for gestational age (SGA) and late fetal death were intermediate between those of Maori and Pacific women. AIMS: To examine trends in preterm birth, SGA and late fetal death for European/other women during 1980-2001 and to explore risk factors which make this group vulnerable to adverse birth outcome. METHODS: De-identified birth registration data from 1 189 120 singleton live births and 5775 stillbirths were analysed for 1980-2001. Outcomes of interest included preterm birth, SGA and late fetal death while explanatory variables included maternal ethnicity, age and NZ Deprivation Index decile. Trend analysis was undertaken for 1980-1994 and multivariate logistic regression was used to explore risk factors for 1996-2001. RESULTS: During 1980-1994, rates of preterm birth rose by 30% for European/other women, in contrast to a non-significant decline of 7% for Maori women and 4% for Pacific women. Rates of SGA declined 19% for European/other women, compared to 25% for Maori and 30% for Pacific women. Preterm birth and SGA were positively associated with teenage pregnancy and increasing NZDep deprivation. During 1980-1994, rates of late fetal death declined by 49%, with declines being similar for all ethnic groups. CONCLUSIONS: The progressive rise in preterm birth during the past two decades is a cause of concern for European/other women, particularly as it appears confined to this ethnic group. While rates of SGA have declined, albeit at a slower rate than for other ethnic groups, the elevated risk amongst teenagers and those living in the more deprived NZDep areas suggests that greater gains are achievable if interventions are targeted towards these particular groups.