Why and How to Medically Induce Labor

Every expectant mother wants to have normal delivery of a healthy baby near her due date. In a normal pregnancy, labor starts on its own any time between weeks 37-42. Sometimes it is safer to have the baby than to continue the pregnancy. In these pregnancies labor is started artificially to deliver the baby before natural labor begins to reduce the health risks of the mother or baby. Or, labor may have started on its own, but problems arise that put you or your baby at risk. Labor that is started early or stimulated to speed up labor is called induced labor.

There are three stages of labor:
First stage: active labor; this stage is the longest. It begins with the onset of regular contractions of the uterus and ends when the cervix has completely dilated to 10 cm.
Second stage: pushing phase which begins at the end of the first stand and ends with the birth of the baby
Third stage: delivery of the placenta; this stage is the shortest. It begins after the baby is born and ends when the placenta and membranes are expelled.

You may also want to read our article on How will I know when I’m in labor?

Reasons for Inducing Labor

Since 1999, induction rates have shown that 1 in 5 births has been induced. The two most common reasons for inducing labor are high blood pressure (gestational hypertension) and prolonged pregnancy (going past your due date). In addition to health reasons, labor may be induced because the mother asks to be induced, called elective induction. Prior to elective induction, the gestational age and maturity of the fetus has to be determined. The following are reasons where induced labor is recommended.

Going past your due date: For most women, labor begins by week 40. However, doctors may wait until the 42nd week (2 weeks after the estimated due date) to declare the mother overdue and recommends induced labor.

Nonfunctioning placenta: The placenta carries food and oxygen from the mother’s blood stream to the fetus. After 42 weeks, the placenta may stop functioning and pose a danger to the health of the fetus.

Broken bag of waters: In a normal pregnancy, when the amniotic sac breaks it is a sign that labor is starting. Sometimes, the bag of waters breaks, but labor contractions do not begin.

Restart or stimulate labor: If initial normal labor slow downs after several hours, artificial stimulation may be used to restart contractions.

Health issues of the mother: If the mother has diabetes, hypertension, heart disease, pulmonary disease, abruptio placentae, an infection or other health issues that might put the mother or baby at risk, inducing labor can prevent complications of birth.

Fetal growth: If the fetus is not growing at is should.

Fetal death.

Problems With Being Overdue

Ultrasound of BabyThere are health problems that can occur after the due date for both mother and baby. The major problem that arises is after 42 weeks gestation is death of the fetus.

When a pregnancy goes past the due date, the physician may order test to check the health of the baby. These test include a non-stress test or an ultrasound. The mother may also be asked to monitor all movements the baby makes, called “kick counts.” Learn more about kick counts and how to do them.

Criteria for Induction

The following situations are suitable to induce labor:
• The presenting part of the fetus is engaged in the pelvis
• There was no previous cesarean birth using a classic uterine incision
• There is enough room for the baby to get through the mother’s pelvis
• No problems with the baby’s heart rate and baby is not in distress
• If the placenta has started separating from the wall of the uterus, but there is no major bleeding
• Placenta previa or vasa previa are not present
• No active genital herpes infection
• Definite signs that normal labor is slowing down

In addition to the above requirements of the mother and baby, the hospital staff should be competent and available to administer and monitor mother and baby during the induction process and have all necessary equipment for monitoring. There should also be a doctor available that can perform a cesarean section.

The following are reasons why labor should not be induced and are similar to those for mothers who should be prevented from having normal (spontaneous) labor.
• The baby is in a transverse position (lying sideways instead of head or feet down)
• The umbilical cord has dropped down into the vagina instead of the baby
• The mother had a previous cesarean with a classic incision in the uterus
• The mother has a transfundal incision in the uterus from prior surgery (such as fibroid removal)
• The blood vessels of the placenta present before the fetus (vasa previa)
• The placenta has grown over the opening of the cervix (complete placenta previa)
• The mother has an active genital herpes infection

Labor is seldom induced on when the mother is having twins, has had more than 5 pregnancies, or there is excess fluid in the amniotic sac (polyhydramnios).

Medical Ways to Induce Labor

There are many medical ways to induce labor, but we will address the ones most commonly used. These methods may be used alone or together.

Cervical Ripening Agents

As labor approaches there are changes in the cervix which cause to thin and open so the baby can pass through. The cervix also becomes soft, called “ripening” so that it is able to stretch during labor. The condition of the cervix is the most important factor in successfully inducing labor. A cervix is considered ripe when it is soft, anterior, effaced more than 50%, and dilated 2 cm or more. When ripening has not occurred there is an increased chance of a long labor, a reduced oxygen supply to the baby and ultimately a cesarean birth.

A Bishop Score is one way of determining whether induced labor will be successful. A Bishop Score takes into account these factors:
• dilation (opening) of the cervix – greater than 5 cm is best with a score of 3
• consistency of the cervix – soft is best with a score of 2
• effacement (thinning) of the cervix – greater than 80% is best with a score of 3
• position of the cervix – anterior is best with a score of 2
• station of the fetus – +1 or +2 is best with a score of 3

Each factor can receive a score of 0-2 or 0-3, with a maximum total score of 13. The higher the score, the more likely labor induction will be successful. A Bishop Score of 8 or more is similar to that for spontaneous labor and is favorable for induction. A Bishop Score of less than 6 usually means cervical ripening agents are needed before using other methods of inducing labor.

Recent studies have shown that other factors can affect a successful induction including the mother’s age, weight, height, body mass index and previous pregnancy history.

The first step in labor induction is ripening the cervix with substances like prostaglandin. Dinoprostone a synthetic prostaglandin that is inserted in the vagina to “ripen the cervix.” After the dose has been given you should remain lying down for up to 2 hours. A second dose may be given after 6 hours if the first dose does’nt produce the desired response. This induces gentle labor. Dinoprostone may also be used along with Pitocin and/or an amniotomy). The ripening of the cervix helps the other induction methods to be more effective. Depending on the type of Dinoprostone used, oxytocin can be started within 1/2 to 12 hours later.

Side effects of Dinoprostone include:
• Upset stomach
• Vomiting
• Diarrhea
• Dizziness
• Flushing of the skin
• Headache
• Fever

Amniotomy

During normal active labor, the amniotic sac may break and contractions will start or become more intense. An effective way of inducing or speeding up labor is by breaking amniotic sac (bag of waters) called artificial rupture of membrane. The amniotic sac is ruptured using a hook-like instrument causing the amniotic fluid to run out and putting pressure on the cervix. This increased pressure on the cervix makes contractions start or get. Amniotomy is a pain-free process and is effective in most cases in starting labor. If labor doesn’t start after breaking the amniotic sac or labor starts but does not progress as it should, IV oxytocin may be given.

Synthetic Hormones

Oxytocin is a natural hormone that stimulates the uterus to contract. During labor, contractions help push the baby through the birth canal and deliver the placenta (called after birth). After delivery of the placenta, oxytocin helps contract the uterus and stops the bleeding. Synthetic versions of oxytocin (Pitocin, Syntocinon or a generic version) are used to induce labor, contract the uterus, and control postpartum hemorrhage. Pitocin is given through an intravenous (IV) tube (placed in the arm or hand) to start or strengthen labor contractions. Pitocin cannot be given by mouth because digestive juices keep Pitocin from working. Pitocin can be used or in combination with breaking of the amniotic sac to induce labor. The amount of Pitocin administered depends on the mother’s ability to accept it. Pitocin is monitored and increased at regular intervals until a good contraction is attained. With an IV, Pitocin can be stopped at any time and it’s effects on the body usually stop quickly after stopping the Pitocin.

Pitocin can be given in a low-dose or high-dose. The higher dose of Pitocin makes labor and delivery go more quickly. Pitocin is used along with amniotomy and the amniotic fluid is checked to see if the baby is having problems. A fetal heart rate monitor is also used during labor to monitor the length and strength of the contractions and the heart rate of the fetus. A baseline for the fetal heart rate (FHR), the mother’s vital signs, and uterine activity is measured and recorded before Pitocin is given. An initial vaginal exam will be done to determine cervical effacement and dilation, and the presentation and station (how far down in the pelvis the fetus has moved) of the fetus. The mother is either in a sitting position or lying on her left side. Pitocin will be started through an IV at a low dose and gradually increased until the contractions are in the desired pattern of 3 contractions every 10 minutes lasting 40-60 seconds each and 1 minute between each contraction. (A normal contraction pattern in active labor is contractions about every 2-3 minutes and lasting about 60 seconds.) This dosage should dilate the cervix at the rate of 1 cm per hour during active labor. When labor progresses to 5-6 cm dilation, the amount of Pitocin can be reduced. Pitocin is often stopped after the cervix dilates to 7-8 cm.

Over stimulation of the uterus may harm the baby or mother. If the contractions are too strong, the uterus can rupture. If the contractions occur more often than 4 every 10 minutes and last 90 seconds or more without a period of rest between them, then Pitocin is decreased or stopped. Too many contractions in a short time for an extended period can keep the fetus from getting a good exchange of oxygen and waste through the placenta. During a contraction, blood flow through the uterus slows down; as the contraction eases up, blood flow resumes and by the end of the contraction, blood flow is back to normal. But, if the contractions are strong enough, all blood flow through the uterus will stop. Pitocin can be stopped if the fetus shows distress on the heart rate monitor. The baseline fetal heart rate is normally between 120 and 160 beats per minute (110 to 160 at full term).

If labor does not start or progress is not made within 2 to 3 hours your doctor may stop the induction. In which case, a cesarean may be done to deliver your baby.

Side Effects of Pitocin
For the mother:
• Over reaction to the medicine
• Heart arrhythmia
• Nausea, vomiting
• Rupture of the uterus
• Too much water in the body (water intoxication)

For the fetus:
• Slow heart rate (below 120 beats per minute)
• Heart arrhythmia
• Significant, prolonged overstimulation may cause brain damage or death

Risks and Complications of Inducing Labor

Problems don’t always happen, but some of the complications include:
• Change in the fetal heart rate, fetal distress
• Increased risk of infection in the mother or baby
• Problems with the umbilical cord
• The uterus is overstimulated and the contractions become too strong or too close together
• The uterus can rupture

Inducing labor brings also has added risk because of the need for other interventions such as:
• An IV tube limits activity
• The mother’s activity is limited which can cause phlebitis
• More frequent monitoring of mother and baby is needed
• More pain relief may be needed due to the more painful contractions related to induced labor
• Increase in cesarean birth or instruments (vacuum or forceps) to help with vaginal birth

To reduce pain, most doctors give pain medication, which in turn has it’s own side effects including slowing down labor and limiting the mother’s activity.

When labor is induced, the fetus tends to go into an unfavorable position and forceps or vacuum extraction then becomes a necessity. Failed induction requires a cesarean section to be done right away to prevent problems for baby and mother.

When Labor Induction Doesn’t Work

Although most women do go into labor with one or more of the above methods, there is the chance that the induction will fail. If so, you may need another induction procedure to start labor. Depending on your situation, you may need to stay in the hospital. In some cases you can go home after the induction procedure. If you stay in the hospital, you and your unborn baby will be monitored to see if labor starts or there are problems. If you go home after the procedure, be sure to ask your doctor if there are activities you should avoid and if there is anything special you should do or watch for if your labor begins at home.

Glossary

Amniotic Sac: Fluid-filled sac in the mother’s uterus where the fetus develops.

Cervix: The lower, narrow end of the uterus at the top of the vagina.

Cesarean Birth: Delivery of a baby through an incision made in the mother’s abdomen and uterus.

Placenta: Tissue that provides nourishment to and takes away waste from the fetus through the umbilical cord.

Prostaglandins: Chemicals that are made by the body that have many effects, including causing the muscle of the uterus to contract, usually causing cramps.

Uterus: A muscular organ in the female pelvis that contains and nourishes the developing fetus during pregnancy.

Vagina: A passageway surrounded by muscles leading from the uterus to the outside of the body, also known as the birth canal.

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