Voluntary C-Sections Result in More Baby Deaths


September 5, 2006 | New York Times
By NICHOLAS BAKALAR


A recent study of nearly six million births has found that the risk of death
to newborns delivered by voluntary Caesarean section is much higher than
previously believed.

Researchers have found that the neonatal mortality rate for Caesarean
delivery among low-risk women is 1.77 deaths per 1,000 live births, while
the rate for vaginal delivery is 0.62 deaths per 1,000. Their findings were
published in this month's issue of Birth: Issues in Perinatal Care.

The percentage of Caesarean births in the United States increased to
29.1percent in 2004 from 20.7 percent in 1996, according to background information in the
report.

Mortality in Caesarean deliveries has consistently been about 1½ times that
of vaginal delivery, but it had been assumed that the difference was due to
the higher risk profile of mothers who undergo the operation.

This study, according to the authors, is the first to examine the risk of
Caesarean delivery among low-risk mothers who have no known medical reason
for the operation.

Congenital malformations were the leading cause of neonatal death
regardless of the type of delivery. But the risk in first Caesarean
deliveries persisted even when deaths from congenital malformation were
excluded from the calculation.

Intrauterine hypoxia — lack of oxygen — can be both a reason for performing
a Caesarean section and a cause of death, but even eliminating those deaths
left a neonatal mortality rate for Caesarean deliveries in the cases studied
at more than twice that for vaginal births.

"Neonatal deaths are rare for low-risk women — on the order of about one
death per 1,000 live births — but even after we adjusted for socioeconomic
and medical risk factors, the difference persisted," said Marian F.
MacDorman, a statistician with the Centers for Disease Control and
Prevention and the lead author of the study.

"This is nothing to get people really alarmed, but it is of concern given
that we're seeing a rapid increase in Caesarean births to women with no
risks," Dr. MacDorman said.

Part of the reason for the increased mortality may be that labor,
unpleasant as it sometimes is for the mother, is beneficial to the baby in
releasing hormones that promote healthy lung function. The physical
compression of the baby during labor is also useful in removing fluid from
the lungs and helping the baby prepare to breathe air.

The researchers suggest that other risks of Caesarean delivery, like
possible cuts to the baby during the operation or delayed establishment of
breast-feeding, may also contribute to the increased death rate.

The study included 5,762,037 live births and 11,897 infant deaths in
the United States from 1998 through 2001, a sample large enough to draw statistically
significant conclusions even though neonatal death is a rare event.

There were 311,927 Caesarean deliveries among low-risk women in the
analysis.

The authors acknowledge that the study has certain limitations, including
concerns about the accuracy of medical information reported on birth
certificates.

That data is highly reliable for information like method of delivery and
birth weight, but may underreport individual medical risk factors.

It is possible, though unlikely, that the Caesarean birth group was
inherently at higher risk, the authors said.

Dr. Michael H. Malloy, a co-author of the article and a professor of
pediatrics at the University of Texas Medical Branch at Galveston, said that
doctors might want to consider these findings in advising their patients.

"Despite attempts to control for a number of factors that might have
accounted for a greater risk in mortality associated with C-sections, we
continued to observe enough risk to prompt concern," he said.

"When obstetricians review this information, perhaps it will promote
greater discussion within the obstetrical community about the pros and cons
of offering C-sections for convenience and promote more research into
understanding why this increased risk persists."