Fetal survival following a preeclamptic pregnancy has improved substantially over the last 35 years in Norway, likely due to a reduction in stillbirths and improvements in clinical management, according to a study in the September 20 issue of JAMA.
Preeclampsia (a potentially dangerous condition that may develop in late pregnancy with symptoms that include high blood pressure, fluid retention, excessive weight gain, and the presence of protein in the urine) is a well-known cause of perinatal (occurring during the period around birth) death. Despite improvements in clinical management, preeclampsia often culminates in the delivery of a very preterm infant following medical intervention. Even mild preterm delivery substantially increases the risk of neonatal death. Preeclampsia can progress rapidly, putting both mother and child at severe risk if no action is taken. Medically indicated preterm delivery may help prevent stillbirth. This practice has increased in recent decades, but its net effect on fetal and infant survival has not been assessed.
Olga Basso, Ph.D., of the National Institute of Environmental Health Sciences, Research Triangle Park, N.C., and colleagues examined changes over time in perinatal and early childhood survival in relation to preeclampsia in Norway. The study included data from 804,448 first-born infants with Norwegian-born mothers and registered in the Medical Birth Registry of Norway between 1967 and 2003, including 770,613 pregnancies without preeclampsia and 33,835 pregnancies with preeclampsia.
The researchers found that among preeclamptic pregnancies, inductions before 37 weeks (of gestation) increased from 8 percent in 1967-1978 to nearly 20 percent in 1991-2003. In 1967-1978, more than 25 percent of all infants born before 34 completed weeks died in the neonatal period, as opposed to 5 percent in 1991-2003.
" ... preeclampsia was an important cause of fetal death in Norway during the late 1960s and throughout the 1970s, but its impact has waned. While risk of stillbirth was 4.2 times higher with preeclampsia, it is now only 1.3 times higher. Preeclampsia still carries a 2-fold increased risk of neonatal death, which has changed little over time. This stability in neonatal risk is remarkable, considering the increasing number of very preterm deliveries in recent years resulting from aggressive obstetric management of preeclampsia. Modern medical management of preeclampsia appears to have been effective in preventing fetal death without causing an increase in infant or maternal death," the authors conclude.