Trends in perinatal death rates in Denmark and Sweden, 1915-1990.

Perinatal mortality rate (PMR) is often taken as an indicator of the quality of obstetric care. Its decline started in the early 1940s in Denmark and Sweden, at the same time as in several other European countries, and its development has been strikingly parallel in the two Scandinavian countries. The changes in the mothers' ages and birth order do not coincide with the changes in the PMR. The percentage of children born weighing less than 2500 g has been very stable over time, albeit higher in Denmark. The move towards hospital confinements in obstetric care took place mainly in the 1930s in Sweden, i.e. before the decline started, and in the 1950s and 1960s in Denmark. The factors investigated have contributed very little to explain why the PMR started to decline in the early 1940s. Factors associated with the distribution of perinatal deaths in a population do not seem to be able to explain the changes taking place over time. In the current study it is postulated that factors behind the change in the PMR are improvements in the mothers' health together with the decline in the total period fertility rate from the beginning of this century. With a smaller number of children the risk of infection was reduced and the amount of food available to each child and pregnant woman increased. This better health in early life may be associated with improved reproductive health in the adult years.