Fewer Stillbirths From Preeclampsia

RESEARCH TRIANGLE PARK, N.C., Sept. 20 -- More aggressive management of pregnancies with preeclampsia has appeared to have a big payoff for fetal survival, as shown by registry data in Norway.

In a review of more than 800,000 births in Norway from 1967 to 2003, investigators here and in Norway found that the likelihood of a stillbirth from a preeclamptic pregnancy had become barely higher than that of non-preeclamptic pregnancies.

This compared with the likelihood of a stillbirth from a preeclamptic pregnancy in the late 1960s that was four times greater than normal pregnancies, they reported in the Sept. 20 issue of Journal of the American Medical Association.

Although their findings apply specifically to Norway, they would likely apply to other industrialized nations with similar facilities and medical practices, noted Olga Basso, Ph.D., of the National Institute of Environmental Health Sciences here, and colleagues at the University of Bergen and Norwegian Institute of Public Health.

Much of the improvement appears to have come from advances in medical management of preeclampsia, the investigators wrote.

Yet they also found that while there was a large reduction in stillbirths and a significant increase in induced pregnancies before 37 weeks gestation, the relative risk of neonatal death following a preeclamptic pregnancy was largely unchanged, suggesting that the increase in presumably risky preterm births was offset by improvements in care of extremely premature neonates.

"Preeclampsia still carries a twofold increased risk of neonatal death, which has changed little over time," they wrote. "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 investigators drew on the comprehensive Medical Birth Registry of Norway for their data, focusing on the effect of early delivery of preeclamptic pregnancies on fetal and infant survival.

They reviewed registry data on 804,448 singleton first-born infants born in the period spanning 1967 to 2003. The main study outcome was the odds ratio for fetal and early childhood death in relation to preeclampsia.

They found that among the 33,835 pregnancies with preeclampsia, inductions before 37 weeks of gestation increased from 8% in the 1967-1978 period to nearly 20% in 1991-2003.

The increase in planned preterm births accompanied a drop in the odds ratio for stillbirth in preeclamptic pregnancies from 4.2 (95% confidence interval 3.8-4.7) in 1967-1978, to 1.3 (95% CI, 1.1-1.7) in 1991-2003.

During the same time spans, however, the odds ratio for neonatal death (days 1-28 of life) were virtually unchanged, at 1.74 (95% CI, 1.44-2.11) in 1967-1978, and 1.98 (85% CI 1.50-2.61) from 1991-2003. Rates of later infant and childhood mortality also showed little change, the authors noted.

"While our data strongly suggest that medical interventions in the management of preeclampsia have benefited the fetus (and, presumably, the mother)," the authors wrote, "these results do not per se imply that early interruption of pregnancy is justified; factors other than early termination have probably contributed as well."

They acknowledged that physicians must balance the risks to the fetus of preterm delivery against the risks to the mother from preeclampsia.

"Our data suggest that, in Norway at least, all these decisions have worked to the net advantage of the child, while achieving a low maternal mortality rate," the investigators wrote.