Delivering Small Babies Raises Future Stillbirth Risk

Experts stress the overall risk of problems remains low

WEDNESDAY, Feb. 18, 2004 (HealthDayNews) -- Women whose first baby was small, especially if it was delivered early, have a higher risk of having a stillborn baby on subsequent deliveries.

Even among these high-risk women, however, the odds of a stillbirth were low. "Ninety-eight times out of 100, the next pregnancy had a live-born baby," says Dr. Mark A. Klebanoff a researcher at the National Institute of Child Health and Human Development. "The absolute risk is not horribly high. It's not so high that somebody should necessarily be discouraged."

Klebanoff is co-author of a perspective article that accompanies a study on stillborn babies appearing in the Feb. 19 issue of the New England Journal of Medicine.

Although the causes of stillbirth are often unknown, experts do know fetuses that are small for gestational age are more likely to be stillborn, especially if they are delivered early. A woman who has had one stillborn baby also has a higher risk of having another.

"[The study] suggests that women with a history of previous preterm delivery, particularly when the baby was born too small for gestational age, are at higher risk of having a subsequent stillbirth," says Dr. Jerry Gilles, an assistant professor of obstetrics and gynecology at the University of Miami School of Medicine. "Usually people are at risk of suffering from the same condition that they previously suffered from. What's interesting is that in women with a previous preterm delivery or baby born too small for gestational age is at risk for something else, for having a stillbirth."

The researchers looked at more than 410,000 women in Sweden who had had two successive births between 1983 and 1997. Within this sample, there were 1,842 and 1,062 stillbirths during the first and second pregnancies, respectively.

Women whose first baby was born early or was smaller than average (or both) had an increased risk of stillbirth during the second pregnancy. This was compared to women whose first baby had a normal gestation and a normal weight.

Specifically, women with a first infant who was born at term but who was small had about double the increased risk for stillbirth during a later pregnancy. The risk was more than triple among women whose first baby was moderately preterm (32 to 36 weeks of gestation) and small. The risk was fivefold among women whose first infant who was both preterm (before 32 weeks of gestation) and small.

Women who had had a first stillborn infant were at 2.5 times the risk of another stillbirth when compared to women whose first infant was not stillborn.

It's not clear what all the underlying causes might be, although some factors, such as intrauterine malnourishment, may underlie both the risk of stillbirth and small babies.

As the perspective article points out, one-quarter of fetal deaths remain unexplained even after examination of the fetus and placenta.

"[This study] raises the index of suspicion and care that we should be telling our patient," says Jay P. Goldsmith, chairman emeritus of the Department of Pediatrics at the Ochsner Clinic Foundation in New Orleans. "We've made a two-thirds reduction in fetal mortality in the last 50 years. We've picked all the low-hanging fruit. The easy ones to fix, we've fixed."

What remains is trying to make a dent in the remaining cases.

"It's an important paper that would point to us that we need to evaluate interventions and see if they make a difference," Gilles says. "The absolute number of women having stillbirth, even with a history that puts them at risk, is low. Certainly there is room for making those numbers even lower and that's where interventions my make a difference."

More information

The March of Dimes has information on stillbirth. Premature Baby-Premature Child has more on babies who are born early.

SOURCES: Mark A. Klebanoff, M.D., researcher, National Institute of Child Health and Human Development, Rockville, Md.; Jay P. Goldsmith, M.D., co-director, nurseries and chairman emeritus, department of pediatrics, Ochsner Clinic Foundation, New Orleans; Jerry Gilles, M.D., assistant professor, obstetrics and gynecology, University of Miami School of Medicine; Feb. 19, 2004, New England Journal of Medicine
Consumer News