Preterm birth in Sweden 1973-2001: rate, subgroups, and effect of changing patterns in multiple births, maternal age, and smoking.

Abstract

The objectives of this report are to evaluate changes in the preterm birth rate in Sweden 1973-2001. Furthermore, describe the proportion of spontaneous and indicated preterm births and assess risk factors for the subgroups of preterm birth during the period from 1991 to 2001.