Few placentas are delayed beyond 20 minutes.(Obstetrics)

SCOTTSDALE, ARIZ. -- Researchers stopped a randomized, controlled trial comparing strategies to prevent postpartum hemorrhage when they found a 20-minute delay in delivery of the placenta to be much rarer than reported in the medical literature.

The investigators, who had expected 8% of women to take longer than 20 minutes, concluded that the third stage of labor exceeds this time frame in just 0.5% of pregnancies. Only 8 of the first 1,607 women recruited for the study took longer than 20 minutes to deliver the placenta, Everett F. Magann, M.D., reported in a poster at the annual meeting of the Central Association of Obstetricians and Gynecologists.

The multicenter trial was designed to determine whether 20 minutes would be a more optimal cutoff than 30 minutes for manually removing a placenta that had not delivered spontaneously. It also assessed risk factors for postpartum hemorrhage.

The investigators concluded that the new information from the aborted study "suggests that placental delivery should be considered earlier, perhaps at 10 minutes."

Dr. Magann of the Naval Medical Center in Portsmouth, Va., said in an interview that they are redesigning the study to consider a cutoff of 10 minutes. "We think that is an appropriate place to look next," he said.

Meanwhile, he and his colleagues stopped recruitment in the United States and Australia, as the original 7,300-woman goal could not produce statistically significant results on the study's primary end points with so few women reaching 20 or 30 minutes. "We saw we would need 110,000 women to get sample size," he said.

Guidelines for manual delivery of the placenta are based on studies that are 15-20 years old, according to Dr. Magann. He noted that some practice guidelines are based on just one study, and others were never tested in clinical trials. He said, "I like to look at it again and say, 'Is that right?'"