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http://www.nytimes.com/2003/02/07/health/07BIRT.html?tntemail0

Hormone Cuts Risk of Premature Birth

By DENISE GRADY

octors reported yesterday that they had for the first time found a way to reduce the rate of premature births in women at risk of having their babies too early.

The treatment, weekly injections of a form of the hormone progesterone, lowered the rate of premature births by more than a third. The hormone is readily available.

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"This is the first real success we've had in dealing with the biggest problem in obstetrics, which is preterm birth," said Dr. Paul Meis, a professor of obstetrics and gynecology at Wake Forest University in Winston-Salem, N.C., who led the study. In fact, the treatment is considered so effective that the study was halted early because it would have been unethical to continue to administer a placebo to some of the high-risk women in the study group, 459 women at 19 medical centers around the United States. Dr. Meis presented the study yesterday at a conference, but it has not yet been published in a medical journal.

Nearly a half-million babies are born premature each year, about 12 percent of all live births. Babies born too soon are often desperately ill, with lung problems and other disorders. They can develop conditions like cerebral palsy, mental retardation, hearing loss or blindness.

Prematurity, which has increased by 27 percent in the United States since 1981, is the leading cause of death within the first month of life.

Infants are considered premature if they are born before 37 weeks; a normal pregnancy lasts 40 weeks.

Women in the study were at high risk because they had histories of giving birth early. About two-thirds of them received the injections; the rest were given placebo shots.

Dr. Meis presented the findings in San Francisco at a meeting of the Society for Maternal-Fetal Medicine. The study was sponsored by the National Institute of Child Health and Human Development.

Dr. Catherine Spong, chief of the pregnancy and perinatology branch at the institute, said of the treatment: "It's very exciting. It works."

Researchers cautioned that the treatment was used to prevent early labor, not to treat women whose labor had already begun.

"It's much easier to prevent the process that ultimately leads to preterm birth than to try to intervene once that process has started," Dr. Meis said. He added that bed rest and various drugs had been used to try to halt early labor but that they had "not proved very effective."

Various conditions can cause premature birth, including infections, drug and alcohol use, extremes of weight or age in the mother and carrying more than one fetus. But in about half of all cases, the premature labor occurs spontaneously and for no known reason.

The hospital stay for a premature baby in 2000 averaged $58,000; the cost was $4,300 for a typical newborn.

Dr. Meis, the study's leader, said that the hormone used in the study — 17-alpha-hydroxyprogesterone caproate, or 17P — was an approved drug, already on the market for other uses, and that obstetricians would be able to obtain it to treat high-risk patients. In the study, the injections were started at 16 to 20 weeks of pregnancy and stopped at 36 weeks.

Dr. Nancy Green, medical director for the March of Dimes, which was not involved in the study, said: "We are thrilled. The problem has been getting worse, not better. Very little progress has been made in prevention. That's the excitement of this finding. We may be at the threshold of discovery of a new and effective means of prevention. If this finding holds up, it will really be a breakthrough in the treatment of the very women for whom treatment is most needed."

Dr. Green said her only reservation about the study was that it had not yet been published.

The women in the study were all pregnant with one fetus; their only known risk factor was a history of having given birth prematurely. But that history put them in the very highest risk group. Some had given birth to babies who died or were severely disabled from being born too young, Dr. Meis said. More than half the participants, 59 percent, were black. The rate of preterm births among black women is 1.5 times that of whites, according to the March of Dimes.

The hormone had a substantial benefit. In the placebo group, 54.9 percent of the women gave birth before 37 weeks, compared with 36.3 percent of those who got hormone shots. The difference translates into a risk reduction of 34 percent.

The difference was even more striking for births occurring before 32 weeks: 19.6 percent in the placebo group and 11.4 percent in the hormone group, for a risk reduction of 42 percent. The results were equal among blacks and whites.

"The rate of preterm birth in this trial was very high in both the drug and placebo groups, but it was much better in the ones who received the drug," Dr. Meis said. "It's not the answer to all preterm birth, and there's certainly a need to understand the process better and try to find other therapies, but this is a first."

Dr. Spong and Dr. Meis said that some smaller studies in the past 20 or 30 years had suggested that progesterone might help prevent early labor but that none of those earlier studies were large or rigorous enough to provide proof.

How progesterone helps is not known. Normally, it is made by ovaries and sustains the pregnancy for the first 10 to 12 weeks, Dr. Spong said. Then the placenta makes it.

Dr. Meis said the researchers who conducted this study are planning another one, in which women are given 17P along with omega-3 fatty acids, which are found in fish. Deficiencies in those fatty acids have been linked to premature birth, and the team hopes to find out whether providing them can produce an even stronger benefit than 17P alone.

Dr. Green said, "The dream goal for this kind of clinical research would be to identify women at risk before they've ever had a preterm delivery and prevent that, and to identify women for whom this particular treatment would be most effective."

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