What defines 'low birth weight' in Pacific infants born in New Zealand?

To report the combined and ethnic specific proportions of preterm and low birth weight (LBW) births, and average birth weights, for New Zealand's four major Pacific ethnic groups (Samoan, Tongan, Cook Island Māori, Niuean).

Data were gathered from the Pacific Island Families Study (PIFS). Mothers of a cohort of 1398 Pacific infants born in South Auckland New Zealand (NZ) during 2000 were interviewed when their infants were 6 weeks old. Birth outcome data were obtained from hospital records on receipt of full informed consent.

Of the Pacific ethnic groups preterm rates ranged from 5.3% to 8.3% (7.3% overall), LBW rates ranged from 3.4% to 5.7% (4.0% overall), and average birth weight of full-term deliveries ranged from 3467 gm to 3751 gm (3664 gm overall). Cook Island and Niuean infants were significantly lighter than Samoan infants. Infants of Pacific born mothers were significantly heavier than infants born to NZ born Pacific mothers. There were no differences observed between infants of 'ethnically homogenous' parents compared 'ethnically heterogeneous' parents. The 10th percentile for all Pacific ethnic groups ranged from 2894 to 3065 grams.

These data reaffirm that infants of various Pacific ethnic groups are larger than other New Zealand infants. Furthermore, analyses of the PIFS cohort suggest that a LBW threshold for NZ born Pacific infants of 3000 grams may be more appropriate.