(Ivanhoe Newswire) -- Inducing labor doesn't increase a woman's risk for
cesarean section delivery in childbirth, scientists at the University of
California, San Francisco and the Stanford University School of Medicine have
found.
"It appears there is misunderstanding regarding the association of increased
cesarean deliveries with elective induction of labor, a procedure which has been
rising in frequency," Aaron Caughey, MD, PhD, lead author of the paper and a
UCSF associate professor of obstetrics, gynecology and reproductive sciences was
quoted as saying. "However, our findings need to be tempered with women's and
physicians' expectations of choosing to induce labor."
"Elective induction can be done in such a way as to avoid raising c-section
rates – it's possible," Douglas Owens, MD, director of the Stanford-UCSF
Evidence-based Practice Center, and an author of the study was quoted as saying.
Owens is a senior investigator with the Veterans Affairs Palo Alto Health Care
System and a professor of medicine at Stanford.
The scientists reviewed existing research that examined elective induction of
labor, in which labor is induced by choice rather than for medical reasons. The
majority of the research findings were limited to women who were about one week
past their due date.
Although the rate of elective inductions has more than doubled since 1990, the
practice has been poorly studied, and physicians have worried these inductions
exposed women to higher risk for cesarean section and the medical complications
that can follow a surgical delivery, according to the research team.
But physicians' concerns may be unfounded. The confusion arises in part from a
flaw in the observational studies that link elective induction to higher
cesarean risk, Owens said. Observational studies usually compare electively
induced labor at a particular gestational age with spontaneous labor at the same
time in pregnancy.
"That comparison is misleading because it doesn't reflect the clinical decision
that women and their physicians must make," Owens said. “Women and their doctors
can't decide to start spontaneous labor on a particular date; they can induce
labor or wait. The risks of induction must be weighed against the risks of
staying pregnant. Near the end of gestation, as the fetus gets bigger, staying
pregnant increases a woman's chance of needing a cesarean. And past the full
gestational period of 40 weeks, the placenta may transmit oxygen to the fetus
less efficiently. Thus, in labor, there may be an increased need to deliver via
cesarean to prevent fetal distress.”
To ensure that their research evaluated the choices women and physicians must
make, the team reviewed randomized controlled trials that assigned women to an
elective induction group or to an "expectant management of pregnancy" (waiting)
group at a particular time in late pregnancy. These studies indicated that
elective induction of labor at or after 41 weeks gestation lowered cesarean risk
by 22 percent compared to waiting. Too little research had been done on elective
induction earlier in pregnancy to draw conclusions about it.
The researchers also observed that women whose labor was electively induced were
half as likely to have meconium-stained amniotic fluid, a sign of fetal stress.
Both findings suggest elective inductions may be safer than continuing pregnancy
past 41 weeks.
There's an important caveat to these results. Obstetricians need to be patient
enough to see if the induction is working before deciding to try a cesarean, the
research team noted. "We're concerned that our findings may not translate to
many hospital settings in the United States," said Caughey. “Most of the studies
reviewed were done at academic medical centers, and many were conducted in other
countries,” he said, noting physicians in different settings may allow different
amounts of time for an induction to work. Prior research indicates that doctors
often tend to proceed from starting an induction to cesarean fairly quickly.
But the take-away message for pregnant women, said Owens, is still that
induction can be done without increasing cesarean risk if obstetricians are
willing to give induction of labor sufficient time to work. "Women should talk
with their physician about how they would handle induction and what their
approach to the procedure would be," he suggested.
Further analysis of elective induction of labor in a variety of settings is
badly needed, Caughey added. In addition to assessment of the risks of elective
induction, researchers need to explore whether the procedure is cost-effective,
since each induction adds about $3,000 to $5,000 to the cost of birth. "It's
pretty surprising that something obstetricians do all the time hasn't been
studied all that well," he said. "If you're dealing with pregnant women, you
don't want to take any unnecessary risks."
SOURCE: Annals of Internal Medicine, August 18, 2009
