By LAURIE TARKAN

eonatal care has been a remarkable success story. Today, babies born at 28 weeks have about a 90 percent chance of survival with no serious long-term health problems, and about half of the babies born as early as 24 weeks, weighing a mere 1.5 pounds, survive.

But this very success has diverted attention from the slight progress made in preventing babies from being born prematurely in the first place.

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Dr. Charles Lockwood, 47, a leading researcher in the field and the chairman of the department of obstetrics and gynecology at the New York University School of Medicine, put it more bluntly.

"Everything we've done so far has been a miserable failure," Dr. Lockwood said. "And it isn't only that we haven't been helpful; we've been harmful up to this point."

Researchers have made inroads into understanding why women deliver prematurely. But most clinical studies using interventions intended to prevent early deliveries — like better prenatal care, drugs that prevent contractions and hospitalization — have failed. Many of the interventions have in fact led to higher rates of preterm babies.

This is all the more frustrating to Dr. Lockwood in light of recent data showing that the rate of premature babies has risen in recent years, from 9.8 percent in 1985 to about 12 percent today. Evidence suggests that very premature babies have more health problems later in life and a higher risk of learning disabilities than their full-term peers.

The March of Dimes, concerned that progress was too slow, began the Perinatal Epidemiological Research Initiative, which has offered $3.75 million to six researchers, including Dr. Lockwood.

Q. Why has research into the prevention of premature births been disappointing?
A. If I knew the answer, we'd be having this Q & A in Stockholm and I'd be about to pick up the big prize. The simplest answer is that most preterm deliveries occur because in all likelihood the mother or the fetus would be better off delivered. We're trying to stop something that very often nature doesn't want us to stop.

We, in our very naïve thinking, initially said we'll just slow down these contractions. Well you know what? Contractions have very little to do with the story. I think we're just beginning to appreciate the fact that there are so many parallel pathways that can lead to prematurity, and as we try to stop one, another one picks up the slack. Nature has built in all sorts of redundancies to protect the mother or the baby.
Q. What accounts for the rising rates of premature births?
A. The biggest factor has been the advancements in assisted reproductive technologies that have led to a rise in multiple births, which tend to be delivered preterm.
Q. Many of us think of premature birth as a spontaneous event, but you believe it's the result of a process that started early in the pregnancy?
A. Exactly, and I suspect it may be genetic or may occur even before a woman gets pregnant.
Q. Along with the twins factor, researchers have identified three other causes of preterm births: vaginal infections, uterine bleeding and stress. Can you explain these?
A. The first is due to bacteria being present in the uterus, either before or after conception. These infections are more common in women with bacterial vaginosis or sexually transmitted diseases, and account for about 40 percent of preterm deliveries. In general, infections are more common in poor, young, unmarried and minority women.
Q. Uterine bleeding occurs when the placenta separates from the uterine wall. How does this lead to preterm labor?
A. The bleeding causes the generation of thrombin, a clotting factor. Thrombin causes an outpouring of enzymes that can break down the fetal membrane, leading to preterm membrane rupture. It also binds to receptors on uterine muscle cells to trigger contractions. Cigarette smoking, cocaine use and high blood pressure have been linked to abruptions, but women with a genetic predisposition to clotting are at high risk.
Q. You mentioned stress as a factor in premature deliveries. What level of stress are we talking about?
A. There's good evidence that high levels of anxiety, depression and major life events like loss of a job, death of a family member, divorces, are associated with higher rates of prematurity. It's a weak association, but it seems to be significant.

The more striking link, though, is with fetal stress, and there's lots of evidence that the placentas of many women who deliver prematurely have impaired blood flow, which we know can lead to fetal stress. Smoking, clotting abnormalities and first pregnancies are associated with impaired flow.
Q. Is there any evidence of pregnant women having a higher incidence of prematurity after 9/11?
A. We're looking at that as we speak. My sense is that acute stress is probably not as bad as chronic stress. So the acute adrenaline rush that happened to those who experienced the attack probably didn't trigger premature delivery. But for those with losses, that stress may be a factor.
 

Q. If we know so much about what is going wrong in premature deliveries, why haven't attempts to prevent them been successful?
A. It seems that once the system is activated, it becomes irreversible. We can slow things down, we can buy some time, but we can't stop the process. We're wasting our time to invent better ways of paralyzing the uterus. Our primary focus needs to be to identify patients who are at risk, and that means understanding the biology and genetics better, then designing effective testing and prevention mechanisms.
Q. In your practice, you treat women with a high risk of preterm delivery. Has your research changed the way you treat them?
A. Yes, we definitely have avoided interventions. Most of our twin moms work right up until they go into labor, whereas in the old days they were all put in the hospital at 28 weeks, which increased rates of preterm births.

We take care of patients with a history of prematurity, and we try to figure out what caused that premature birth. Was it infection, a hemorrhage, stress? We're pretty successful if we can get the patient before she gets pregnant.
Q. When you got into this field, did you know it would be so difficult to crack?
A. Initially I thought, This will be very simple. These people all have infections, we'll give them antibiotics, and they'll get better. But the more data we collected, the more complicated it became, and the more I came to realize that prematurity was just a symptom, really an end product of an incredibly complex process.
 

Dr. Charles Lockwood is a researcher in the field of premature delivery.