Fetal growth restriction and other factors associated with neonatal death in New Zealand.

BACKGROUND

There are few studies of risk factors for neonatal death in Australia or New Zealand.

AIMS: To assess in a cohort of neonatal deaths (i) the demographic and clinical risk factors; (ii) the relationship between low weight for gestation using population and customised centiles; and (iii) the cause of death by the Perinatal Society of Australia and New Zealand Perinatal and Neonatal death classifications.

METHODS

A retrospective study of 410 babies who died, in the neonatal period, at National Women's Hospital, between 1993 and 2000. Demographic and clinical data were compared with that from a referent population of live births with neonatal deaths removed (n=68 905).

RESULTS

The overall neonatal death rate was 5.9 per 1000 live births and after exclusion of congenital abnormalities was 3.9 per 1000 live births. Infants of Maori women had increased risk compared to European (adjusted odds ration (AOR) 1.52; 95% CI 1.06, 2.18), as did those born to primipara (AOR 1.52; 95% CI 1.10, 2.11), mothers with >or=1 previous low-birthweight baby (AOR 2.97; 95% CI 1.99, 4.44), >or=1 miscarriage (AOR 1.35; 95% CI 1.00, 1.81), and an index multiple pregnancy (AOR 10.51; 95% CI 8.04, 13.76). Infants of Chinese mothers had decreased risk (AOR 0.42; 95% CI 0.18, 0.96). Fifty (34%) babies were small for gestational age by customised and 26 (17%) by population centiles. The most common classification of neonatal death was congenital abnormality (34.6%), followed by extreme prematurity (34.1%).

CONCLUSIONS

This study emphasises the importance of suboptimal fetal growth as an important risk factor for neonatal death especially when customised centiles are used.