[Increased birth weights in the Nordic countries. A growing proportion of neonates weigh more than four kilos].

The proportion of children with high birthweights is increasing in Sweden, as in the other Nordic countries. According to the Swedish national birth registry (founded in 1973), the proportion of term (i.e. (37 gestational weeks) offspring of singelton pregnancies, and weighing four kg or more, increased from 16.9 per cent in 1973 to 20.3 per cent in 1995. The respective figures for the first-born subgroup were 12.9 and 15 per cent, the increase in mean birthweight being from 3400 to 3520 g. There was a corresponding increase in head circumference. The risk of delivery-related complications increases with birthweight over four kg, and a higher incidence of major perineal rupture (grade 3 or 4) has been reported, as well as a disturbing increase in the incidence of brachial plexus damage. Findings in recent studies suggest high birthweight to be associated with an increased risk of subsequent morbidity, both in childhood and in adulthood, specifically diabetes type 1, eczema and certain malignancies, particularly breast cancer and prostate cancer. Although the cause of the increasing proportion of large newborns is not known, it may be partly due to weight increase among gravidae. Another possible explanation is reduced maternal smoking, as smoking is less common now than in the 1970s.