Postterm pregnancy risks may be underestimated. (Expectant Management Questioned).

BIG SKY, MONT. -- The rate of perinatal morbidity and mortality is significantly higher in postterm pregnancy, according to the results of a literature review conducted by Dr. David A. Miller.

This finding should be a deterrent to expectant management and a strong argument for induction of labor in women with postterm pregnancy he said at an obstetrics conference sponsored by Symposia Medicus.

There is a common perception, backed by only a few studies, that routine induction of postterm pregnancy increases the rate of cesarean section, said Dr. Miller of the University of Southern California Women's and Children's Hospital in Los Angeles.

"This is the presumption that has led people to want to wait on a postterm pregnancy but that presumption is not correct. The available data in the literature don't support this," he said.

"In an accurately dated postterm pregnancy, with few exceptions, the fetal risks associated with expectant management outweigh any benefits. Induction is indicated at around 40 weeks to ensure a delivery by 41 weeks," he said in an interview.

In a review of 10 randomized controlled trials from the last decade comparing postterm induction to expectant management, 7 studies showed no difference in the cesarean section rate, and 3 found a higher rate of cesarean section and stillbirth in the expectant management group.

The three studies that favored induction of postterm pregnancy reported a cesarean section rate of 19.8% in the induction group vs. 21.9% in the expectant management group and a stillbirth rate of 0.07% in the induction group, vs. 0.21% in the expectant management group.