Induction of
labor is a major component of obstetrics practice with nearly one third of
multiparous women and 43 percent of
nulliparous women undergoing induction.
Mary
Catherine Tolcher, MD, MS, assistant professor of obstetrics, Mayo Clinic
Rochester said “Induction of labor is likely to become more common with
increasing maternal age, hypertensive disorders and obesity,” at Saturday
afternoon Clinical Seminar at the conference.
The leading
indications for induction of labor at the Mayo Clinic are late-term pregnancy,
fetal indications, PROM, gestational hypertension and diabetes.
She further
added that benefits of induced labor are clear, Induced labor avoids maternal
and fetal risks of continuing pregnancy, avoids risks of late-term pregnancy,
allows the timing of labor to be controlled in cases where delivery in a
particular facility is appropriate and may be an alternative to cesarean
delivery.
The risks
are equally clear too, which means prolonged hospitalization before delivery,
increased likelihood of more intrusive interventions, increased risk of
postpartum hemorrhage and increased likelihood of cesarean delivery.
Answering the
key question of whether induction increases the risks of cesarean section she
said that it is like a lot of other things in medicine, and depends on your
comparison group.
Results
based on retrospective cohort data show the following conclusions.
Depending
upon studies the odds ratio for undergoing a cesarean delivery was somewhere
between 1.9 and 3.5 when comparing spontaneous labor and induction.
But compared
to expectant management, induction does not seem to be associated with an
increased risk of cesarean delivery.
The first
randomized control trial of induction vs expectant (ARRIVE TRIAL) management is
currently recruiting participants and will be completing the data collection at
the end of 2016.
Since the
inception of induction of labor, many methods have been in use like mechanical
ripening by Foleys catheter, pharmacological use of prostaglandins and
oxytocin. These are either used alone or in combination with or without
amniotomy.
According to
Dr. Tolcher, clinical trials have shown all of them to be effective. Cervical
ripening is definitely more effective than oxytocin alone, while prostaglandins
and Foleys catheter seems to have the same outcome. Recent data reported at annual meeting of Society
for Maternal-Fetal Medicine in 2016, concluded that time to delivery is
shortened by using combination methods than using each of the method alone with
no increase in cesarean section rates.
Amniotomy is
also effective in augmenting the labor, but when early amniotomy (Cervix < 5
cm dilated) was compared to late amniotomy (Cervix > 5 cm dilated), the latter
seemed more appropriate. Early amniotomy does results in shorter labor time but
it comes with higher incidences of chorioamnionitis and increased fetal cord
compression.
Dr. Tolcher
also said that Mayo clinic has its own protocols for induction and the cases scheduled
for induction in the coming week are reviewed in a staff meeting on Friday and
Labor and Delivery nurse also has a significant say to put a stop to
non-indicated cases.
Current
indication for inductions include advanced maternal age, cholestasis, diabetes,
fetal issues, hypertensive disorders, obesity, preterm premature rupture of
membranes, prolonged pregnancy, prior stillbirth and unstable presentation.
Depending on the indication, the pregnancy must be in week 37 and later.
Cervical
ripening is the initial step, followed by oxytocin as needed and amniotomy at
the discretion of physician. A failed induction is 24 hours of oxytocin or 18
hours of oxytocin plus rupture of membranes.
Before the
decision for induction is taken, the physician should have a very good discussion
with patient about the procedure, the expected time to delivery and slightly higher
odds of having a cesarean delivery.
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