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McKesson Clinical Reference Systems: Women's Health Advisor 2002.2
Induction of Labor
What is induction of labor?
Induction of labor is the use of artificial means, such as a
medication, to start the process of childbirth.
When is it used?
The following conditions may be reasons for inducing labor:
- pregnancy that has continued at least 1 to 2 weeks past
the due date
- the mother has high blood pressure caused by the
pregnancy (called preeclampsia)
- infection of the amniotic sac
- early rupture of the membranes without labor
- poor growth of the baby
- Rh incompatibility between the mother and the baby
- diabetes in pregnancy
- kidney disease
- abnormal fetal heart rate patterns
- separation of the placenta (abruption)
- chronic medical problems of the mother or baby
- logistical reasons (for example, you live too far from a
hospital and you have a history of fast labor)
- psychosocial reasons
- death of the baby before birth.
Before inducing labor, the doctor will check the cervix to
see if it is thin or dilating. The doctor will also check
the baby's position in the uterus. In complicated cases,
the doctor may test the maturity of the baby's lungs by
testing a sample of the amniotic fluid around the baby.
What happens during the procedure?
Labor is induced at the hospital. The most common ways to
induce labor are amniotomy, oxytocin, and prostaglandin gel.
Amniotomy is often the easiest way to start labor. This
procedure is no more painful than a normal vaginal exam.
The doctor uses a special hook instrument to make a hole in
the amniotic membrane. This membrane holds back the bag of
waters. When it is torn (ruptured) and the amniotic fluids
start coming out, uterine contractions usually start.
Amniotomy cannot be done safely if your cervix is not
dilated or if the baby's head is too high in your pelvis.
The doctor may decide to start labor by giving you oxytocin
intravenously (IV). Oxytocin is a natural hormone that
makes the uterus contract. Before oxytocin is started, the
doctor and nurses will check the baby's heart rate. At
first you will get a very low dose of oxytocin. A monitor
will measure your contractions. The dose will be increased
slowly until the contractions reach the desired strength and
frequency. The doctor or nurse will adjust and continue the
oxytocin until the baby is born. If you start contracting
well enough on your own, the medication may be decreased or
shut off.
As another alternative, the doctor may decide to use an
ointment in the vagina called prostaglandin gel. This is
often used when the cervix is thick and undilated (unripe).
The gel helps soften the cervix so that the cervix will thin
and dilate faster. Often the gel is used along with
oxytocin to help the oxytocin work faster and more
efficiently.
During the induction of labor, your contractions, your blood
pressure, how well your cervix is dilating, and your baby's
heart rate will be monitored.
What are the risks associated with this procedure?
The risks of induction of labor with oxytocin can almost
always be prevented by closely adhering to standard
techniques such as close monitoring and a gradual increase
of the dose. There remains a small risk of:
- abnormal fetal heart rate from contractions that are too
strong or frequent, or from a squeezing (compression) of
the umbilical cord
- separation of the placenta from the uterus (abruption) if
contractions are too strong
- water intoxication if the wrong IV solutions are used
- damage to the uterus (for example, a tear or rupture of
the uterus)
- a cesarean delivery if induction of labor does not work.
When such complications occur, the doctor will stop giving
oxytocin and may deliver the baby by cesarean delivery. If
the baby is very far down the birth canal and the cervix is
completely dilated, the doctor may use forceps or suction to
deliver the baby vaginally.
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