Pre-pregnancy risk factors of small-for-gestational-age births and perinatal mortality.

The Scandinavian part of the NICHD study of successive small-for-gestational-age (SGA) births included 5722 parous women from Trondheim and Bergen (in Norway) and Uppsala (in Sweden). Study enrollment took place from January 1986 through March 1988. The aim of the main study was to investigate factors associated with inhibited intrauterine growth. This paper reports on the fetal, perinatal, and neonatal deaths among the births in the study in relation to different risk factors. The cause of deaths were analyzed to see if there were any associations with the risk factors. There was a total of 84 deaths, 65 of these were fetal, perinatal or neonatal deaths and included in this analysis. The remaining 19 are for different reasons excluded. Thirty-two (60%) of the autopsies regarded the high risk group who comprised only 42.4% of the total study population. The high risk group was selected using the following risk criteria: a previous low weight birth or perinatal death, maternal low weight (pre-pregnancy weight < 50 kg), the presence of a chronic maternal disease, and smoking at the time of conception. A significant association was found between perinatal mortality and the presence of one or more of the defined risk criteria (relative risk 2.0; 95% CI 1.2, 3.4). Asphyxia and related disorders was the most important single cause of death and was found to be associated with the maternal risk factors (RR 3.9; 95% CI 1.5, 9.8). A significant association was found between maternal risk factors and SGA autopsies (RR 3.9; 95% CI 1.7, 8.9). No association was found between asphyxia and SGA. It is concluded that women with risk factors based on complications in a previous pregnancy are more prone to stillbirths, perinatal, and neonatal deaths, and with asphyxia as the most prominent cause of death.