Birthweight of single livebirths and weight specific early neonatal mortality in Hungary and Norway.

Comparisons of birthweights of single livebirths in Hungary and Norway reveal distributions to have similar shapes; however, in the case of Hungary the distribution is shifted to the left, i.e. towards lower weights. In the registration of pregnancy outcomes, almost identical definitions are applied in the two countries, and the observed difference in distributions of birthweights is taken to reflect that Norwegian livebirths, are on average about 300 g heavier than Hungarian livebirths. Employing the method of analysis of birthweight and perinatal mortality suggested by Wilcox & Russell, it can be demonstrated that the proportions of births in the residual distributions of birthweights in the two countries are of the same magnitude and that the relative differences in first week mortality risks are similar for all birthweights. These results are taken to support the conclusion that to use a cut-off point of 2500 g in defining low birthweight, which will result in a two fold higher proportion of such infants in Hungary compared to Norway, is unwarranted, as it will falsely convey the impression of relatively more obstetric and paediatric problems in Hungary.