[Regional distribution of birth weights in Denmark during the period 1979-1983].

We investigated the geographical distribution of birthweights among liveborn infants in Denmark for the years 1979-1983, using the Medical Birth Register of the Danish National Board of Health. The investigation includes 272,361 liveborn children. The birthweight varies with the sex of the child, and with the age and parity of the mother. In the analysis of geographical variation of birthweight correction was made for these factors. We found an association between birthweight and urbanization, the lowest average birthweight being found in the capital, and the highest in the rural areas. Further, the average birthweight was higher in the western than in the eastern part of Denmark, especially in Northern Jutland and in Aarhus County. Geographical variation in gestational age explains part of the geographical variation in birthweight, but part of the variation must be explained by variation in the growth of fetuses. The role of genetic variation, variation in living conditions, and variation in the conduct of the health services is discussed. We found an unexpected association between the average birthweight in the counties, and neonatal mortality; the counties with high average birthweights also had a significantly increased neonatal mortalities.