Heavy birthweight in Native Indians of British Columbia.

An unexpected finding of heavy birthweight in one group of Native Indians in Ontario led to this analysis of the occurrence of heavy birthweight in Natives of British Columbia. Canadian Native Indians have high rates of perinatal mortality, usually directly related to low, not high birthweight. Birth statistics of all singleton livebirths during 1982 to 1986 were examined. Heavy birthweight was 50% more frequent among Natives than non-Natives (relative risk 1.47, 95% confidence limits 1.35 and 1.59), after stratification by week of gestation. Stratification was necessary because pre-term births were twice as frequent among Natives as non-Natives (11.4% vs 5.7%). Fetal and neonatal mortality were 40% more frequent in Natives. To explain these findings, a hypothesis is advanced of high rates of glucose intolerance during pregnancy in Natives.