BOSTON (CNN) -- A campaign by U.S. health officials to shrink the number of Caesarean deliveries may lead to higher costs and more complications for mothers and babies, according to an article in the latest issue of New England Journal of Medicine.

In an opinion piece, four obstetricians at Harvard University teaching hospitals said pressure from HMOs and policy-makers is leading some doctors to encourage women to try vaginal delivery even when the risks are higher than those of a Caesarean section.

The U.S. Department of Health and Human Services is campaigning to reduce the C-section rate from 21 percent of all deliveries in 1995 to 15 percent by 2000. The doctors said that while it may be possible to reduce the rate without endangering women or their babies, the 15 percent target is unnecessary and risky.

"Reducing the ... rate to 15 percent may have a detrimental effect on maternal and infant health. There is no evidence to support this target," said Drs. Benjamin Sachs, Cindy Kobelin, Mary Ames Castro and Frederic Frigoletto.

The doctors wrote that C-sections don't necessarily cost more than vaginal deliveries and therefore any campaign to lower C-section rates should not be based on presumed cost savings.

They also said the country's low rates of maternal and infant mortality show that the current C-section rate is reasonable.

One way doctors and hospitals have tried to reduce the number of Caesarean births is to give women who have previously had a C-section the chance to deliver a subsequent child vaginally, which doctors refer to as "a trial of labor."

But the Harvard doctors said such trials can lead to complications, particularly ruptures of already weakened uteruses. The number of uterine ruptures tripled in Massachusetts between 1985 and 1995, and the rate has risen significantly in other states as well, the doctors said.

The doctors suggested that "trials of labor" be offered only at hospitals equipped to intervene in the event of an emergency. And they recommended that doctors should try to bring down the C-section rate by preventing the initial C-section, not by encouraging women who have had the procedure to try vaginal delivery the next time.

Another delivery technique, drawing a baby out of the womb with forceps or a vacuum extractor, may be responsible for an increase in the number of serious birth complications, such as skull fractures, reported to the U.S. Food and Drug Administration between 1989 and 1995.

Damon Thompson, a spokesman for the Department of Health and Human Services, said the 15 percent goal was based on consultation with hundreds of groups and is only a target, not a quota. He said studies have shown that hospitals can lower their C-section rates without compromising safety.

He also pointed out that studies show vaginal deliveries are safer than C-sections for most women, though they are slightly riskier for women with a previous Caesarean. Women who deliver vaginally also spend much less time in the hospital and generally recover more quickly, Thompson said.

However, the Harvard doctors say the 15 percent goal has led some HMOs to pressure hospitals to reduce their C-section rates. Many HMOs discourage C-sections by paying doctors the same amount for vaginal and Caesarean deliveries, and others consider a hospital's C-section rate when deciding whether to include it in their network.

Senior Medical Correspondent Dan Rutz and Reuters contributed to this report.