induction of labor


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Related to induction of labor: elective induction of labor, Bishop score

Induction of Labor

 

Definition

Induction of labor involves using artificial means to assist the mother in delivering her baby.

Purpose

Labor is brought on, or induced, when the pregnancy has extended significantly beyond the expected delivery date and the mother shows no signs of going into labor. Generally, if the unborn baby is more than two weeks past due, labor will be induced. In most cases, a mother delivers her baby between 38-42 weeks of pregnancy. This usually means that labor is induced if the pregnancy has lasted more than 42 weeks. Labor is also induced if the mother is suffering from diseases (preeclampsia, chronic hypertension), if there is an Rh blood incompatibility between the baby and the mother, or if the mother or baby has a medical problem that requires delivery of the baby (like a premature rupture of the membranes).

Description

The uterus is the hollow female organ that supports the development and nourishment of the unborn baby during pregnancy. Sometimes labor is induced by the rupturing the amniotic membrane to release amniotic fluid. This is an attempt to mimic the normal process of "breaking water" that occurs early in the normal birth process. This method is sometimes enough stimulation to induce contractions in the mother's uterus. If labor fails to start, drugs are used.
Most labor is induced by using the drug Pitocin, a synthetic form of oxytocin. Oxytocin is a natural hormone produced in the body by the pituitary gland. During normal labor, oxytocin causes contractions. When labor does not occur naturally, the doctor may give the mother Pitocin to start the contractions. Pitocin makes the uterus contract with strength and force almost immediately. This drug is given through a vein in a steady flow that allows the doctor to control the amount the mother is given.
Sometimes vaginal gels are used to induce labor. Normally, the baby will pass through the opening of the uterus (the cervix) into the birth canal during delivery. Because of this, the cervix softens and begins to enlarge (dilate) during the early part of labor to make room for the baby to pass through. The cervix will continue to dilate, and the contractions will eventually push the baby out of the mother's body. When labor needs to be induced, the cervix is often small, hard, and not ready for the process. The doctor may need to prepare or "ripen" the cervix to induce labor. The hormone prostaglandin in a gel form may be applied high in the vagina to soften and dilate the cervix, making the area ready for labor. This may be enough to stimulate contractions on its own. More often, prostaglandin gel is used in conjunction with Pitocin.
If all attempts to induce labor fail, a cesarean section is performed.

Risks

Once labor has been induced, the unborn baby is monitored to guard against a reduction in its oxygen supply, or hypoxia. The drugs used to induce labor cause vasoconstriction, which can decrease blood supply to the unborn baby. Throughout the process, the baby's heart rate is monitored by an electronic device placed on top of the mother's abdomen. The heart rate is one sign that the unborn baby is getting enough oxygen and remains healthy. Once the membranes are broken, prolonged labor may result in infection to either the newborn or the mother.

Normal results

Once labor is induced and the cervix has dilated, labor usually proceeds normally. When performed properly, induced labor is a safe procedure for both mother and baby.

Resources

Books

Berkow, Robert, et al., editors. The Merck Manual of Medical Information. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

Key terms

Cesarean section — Delivery of a baby through an incision in the mother's abdomen instead of through the vagina; also called a C-section.
Preeclampsia — Hypertension (high blood pressure) experienced during pregnancy.
Rh blood incompatibility — A blood type problem between mother (who is Rh negative) and baby (who is Rh positive), making the immune system of the mother attack her unborn baby. During delivery of the first pregnancy, the mother's immune system becomes sensitive to the Rh positive blood of the baby. The mother's system may then attack later pregnancies and cause severe illness or death to those babies.
Vasoconstriction — Constriction of a blood vessel.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

induction of labor

The use of artifical maneuvers to hasten the onset of labor, including the use of prostaglandin E2 gel, oxytocin infusion, and amniotomy; in post-term pregnancy, induction of labor results in a lower rate of cesarean section than serial antenatal monitoring
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

in·duc·tion of la·bor

(in-duk'shŭn lā'bŏr)
Medical attempt to improve the process of giving birth through drugs or surgical interventions and manipulation.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
Twenty out of 21 hospitals that participated in the PROBAAT study in 2010 returned the survey, revealing that 70% (14/20) used the Foley catheter, 15% (3/20) used prostaglandins, and 15% (3/20) did not offer induction of labor in women with a prior cesarean delivery.
These 80 cases were compared to the data of 160 parous women who had a successful induction of labor (controls) (Figure 1).
Induction of labor and cesarean delivery by gestational age.
A comprehensive meta-analysis of the benefit of induction of labor at or beyond term, estimated that 426 inductions would need to be initiated to prevent one perinatal death.
Methods of cervical ripening and induction of labor. Am Fam Phsician 2003(10); 67: 2123-8.
Active management of risk in pregnancy at term in an urban population: An association between a higher induction of labor rate and a lower cesarean delivery rate.
Most reasonable women considering a trial of labor after a prior cesarean delivery would want to know that spontaneous labor is associated with a tripling of the risk of uterine rupture and that induction of labor with prostaglandins is associated with an increase in that risk by a factor of 15" (10).
Study participants were low-risk nulliparous women with a singleton vertex fetus who were randomly assigned to induction of labor at 39 to 39 4/7 weeks (n = 3,062) or expectant management (n = 3,044) until 40 5/7 to 42 2/7 weeks.
Induction of labor with misoprostol for premature rupture of membranes beyond thirtysix weeks gestation.
This meta-analysis compared the outcomes of routine induction of labor and expectant management for uncomplicated pregnancies after 41 weeks.
Uterine Rupture Among Women Attempting VBAC Number of Incidence Type of Delivery Women (per 1,000) Repeated cesarean without labor 6,980 1.6 Spontaneous onset of labor 10,789 5.2 Induction of labor without prostaglandins 1,960 7.7 Induction of labor with prostaglandins 366 24.5 Relative Type of Delivery Risk Repeated cesarean without labor 1.0 Spontaneous onset of labor 3.3 Induction of labor without prostaglandins 4.9 Induction of labor with prostaglandins 15.6 Source: N.