The New York Times - September 5, 2006 -
Voluntary C-Sections Result in More Baby Deaths
September 5, 2006
Voluntary C-Sections Result in More
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 29.1 percent 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
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.”