Cesareans don't help lowest-weight babies.

Cesareans don't help lowest-weight babies

The surging rate of cesarean deliveries -- which now account for one in four U.S. births -- may be leveling off, but it remains especially high in one category of babies: those weighing 1 to 3 pounds. A new epidemiologic study leads researchers to question the value of surgical delivery for these tiny babies.

Michael H. Malloy and his co-workers at the National Institute of Child Health and Human Development find that cesareans improve the survival chances of these babies only during their first 24 hours. After that, tiny infants delivered surgically have a higher death rate than those delivered vaginally. By the end of one week, no significant survival differences remain, the researchers report in the Sept. 15 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

The team studied birth and death certificates of 3,095 very-low-birthweight babies born in Missouri from 1980 through 1984. Missouri's statistics for cesareans and low-weight births resemble overall U.S. statistics, Malloy says.

During the study period, the percentage of cesarean deliveries rose most dramatically -- from 9 percent in 1980 to 27 percent in 1984 -- among newborns weighing 1 to 1.5 pounds, the lowest weight category studied. This group also seemed to derive more initial benefit from surgical delivery than did the other weight groups studied. About 67 percent of the C-section babies in this category survived their first day, compared with about 41 percent of those delivered vaginally. But on the second through sixth day, the chance of a C-section baby dying jumped to twice that of a vaginally delivered baby. Among infants weighing 1.5 to 3 pounds, delivery methods did not significantly affect overall survival.

The enhanced first-day survival among the tiniest babies may not result from their surgical delivery, Malloy says. "It may not be so much a function of the cesarean section that prolongs the survival of these kids through the first day as it is the availability of resuscitation teams at the time of delivery," he says.

But because the researchers could not verify the presence of resuscitation teams, that conclusion may be unwarranted, says Sharon L. Dooley of Northwestern University Medical School in Chicago. In an editorial accompanying the new report, Dooley emphasizes the study's retrospective nature and the fallibility of birth and death certificates as accurate records. cIn spite of all those problems," Dooley told SCIENCE NEWS, "their analysis was keen and their thesis was right on -- namely that they showed no benefit of cesarean section" to very-low-birthweight infants.