Labor stages

Definition
Labor is a series of contractions in a pregnant woman's uterus that leads to the birth of a baby.

Causes/associated factors
Labor typically happens between the end of week 37 and week 42 of the pregnancy. During labor, the cervix -- the tip of the uterus that extends into the vagina -- effaces (thins) and dilates (opens) to allow the baby to move down the birth canal. We don't know for sure what starts the labor process. There's no way to predict exactly when labor will begin.

Signs/symptoms
There are three stages of labor. In the first stage, the cervix dilates completely. In the second stage, the baby is born. In the third stage, the placenta is delivered.
Stage 1
The first stage of labor is the longest. It may last eight to 24 hours for first-time mothers (primipara) or six to 15 hours for women who have given birth before (multipara).

This stage begins with contractions. Eventually, the contractions become regular, frequent, longer and more intense. The first stage of labor ends when the cervix is completely dilated (to 10 centimeters) and completely effaced. Before or during stage one, you may notice a small amount of clear, pink or blood-tinged mucus from the vagina. This is called the mucus plug or bloody show. Also, the amniotic membrane may rupture. This is often referred to as breaking your water. You may feel a trickle or gush of warm fluid.

Stage 2
The second stage of labor begins after the cervix has fully dilated. It ends when the baby is born. For first-time mothers, the second stage may last up to two hours or more. It can be as short as 20 minutes for some multiparas.

During this stage, the contractions are severe and close together as the baby is pushed through the open cervix and down the birth canal. If your water hasn't already broken, it may do so early in this stage. As your baby moves down the birth canal, you'll feel pressure on your rectum. You'll have the urge to push (bear down), or it may feel like you need to have a bowel movement. Your doctor will let you know when to start pushing.

An episiotomy (a surgical cut in the area between the vagina and the anus) may be done to enlarge the opening for the baby's head. Typically, the baby's head is delivered first, then the shoulders, body and legs. Immediately after birth, the baby may be placed on your abdomen or allowed to nurse. To prevent eye infections, all newborns receive eyedrops shortly after birth.

Stage 3
The third stage of labor begins right after the baby is born. It lasts until the placenta is delivered, which usually takes five to 30 minutes. You may feel moderately painful contractions. Once you've delivered the placenta, you'll be carefully observed for abnormal bleeding or any other complications. If you had an episiotomy, it will be sutured, or surgically stitched, now.


Diagnosis
A physical exam of your cervix will help determine your stage of labor. You'll be diagnosed in active labor when there are painful contractions along with effacement, the bloody show or ruptured membranes.
During labor, electronic fetal monitoring can help ensure your safety as well as your baby's. Electronic monitoring may be done during early labor and then intermittently. In some instances, such as high-risk pregnancies, it's done continually.

External monitors are used most often. The nurse or doctor will secure an ultrasound transducer (an instrument that transmits sound waves) to your abdomen with an elastic strap. Once you're comfortable, the transducer will be attached to an external monitor. The sound waves sent out by this instrument bounce off the fetus to detect the fetal heartbeat, which is then recorded by the monitor on a graph.

Another device, also placed on the outside of your abdomen, records the frequency and length of the contractions. This monitoring helps your doctor identify the beginning and end of each contraction, as well as the baby's response to the contractions.

When the doctor wants more specific information, internal monitoring may be used. Once your cervix is dilated slightly, an electrode is placed on the baby's scalp. This will monitor the baby's heartbeat continuously without the interruptions that can occur with external monitoring. An internal monitor for the contractions may also be placed in the form of a thin tube alongside the baby's head. This makes it possible to also monitor the strength of the contractions, along with their frequency and length.


Treatment
Depending on the circumstances, several treatments may be used during labor and delivery.
Induction of labor
The induction of labor is the initiation of the process of childbirth with artificial methods, such as medications, before labor starts spontaneously. This may be necessary when it's better for you or the baby to deliver earlier, rather than wait for contractions to begin on their own.

If the cervix has not softened and begun to thin, your doctor may apply a medication to the cervix to help it do so. A cervical dilator, a device placed in the cervix several hours before the induction, can also soften the cervix. If this is already happening naturally, there are several techniques that may be used to stimulate contractions, which will open the cervix.

Stripping of the membranes: The lower membranes of the amniotic sac are separated manually from the lower part of the uterus during a vaginal exam.

Amniotomy (artificial rupture of the membranes): A special instrument is inserted into the vagina and through the cervix to the amniotic sac or bag of waters. A tear is then made in the sac and the amniotic fluid comes out of the vagina. The only discomfort you may experience is similar to what you may feel during a routine vaginal exam.

Oxytocin administration: Contractions are stimulated with a synthetic form of oxytocin (Pitocin, for example), the hormone that causes the uterus to contract. Oxytocin is given intravenously.
Pain managament
To manage the pain of childbirth, most women use special breathing methods, such as Lamaze, Bradley or Read. Epidural anesthesia (a local anesthetic injected into the epidural space, the space that surrounds the spinal cord) or certain sedatives, analgesics or other medications may also be used to control pain during labor. If epidural anesthesia is not used, the perineum is sometimes numbed with anesthetic medication just before delivery.

Episiotomy
An episiotomy is an incision made between the vagina and rectum. The incision creates more room for the baby to be delivered and helps prevent the tissues from tearing. After your baby is born, the episiotomy will be closed with stitches. The stitches will self-absorb during the postpartum period, so they won't require removal. If you don't want an episiotomy, ask your doctor about ways to avoid the procedure.

Forceps or vacuum-extraction birth
In rare cases, your doctor may need to use either forceps or vacuum extraction to help deliver your baby. Forceps are tong-shaped instruments that are placed on each side of the baby's head to allow the baby to be pulled out of the birth canal. Vacuum extraction uses a cup-shaped device, which is attached to a machine that produces vacuum pressure. The suction cup is placed on the baby's head and used to pull him or her out of the birth canal. Discuss any concerns you have about these procedures with your doctor.

Cesarean section
A cesarean section (C-section) is the delivery of a baby and the placenta through an incision made in the abdomen and an incision of the uterus. It may be scheduled near your due date or become necessary during labor if conditions develop that would make a vaginal delivery hazardous for you, the baby or both. If you've had a previous C-section, you may be able to deliver vaginally with your next pregnancy. Discuss the risks and benefits with your doctor.


Complications
Possible complications of labor include:
preterm labor (labor that begins before the end of week 37 of the pregnancy)
premature rupture of the amniotic membrane (when the water breaks one or more hours before labor begins)
placenta previa (when the placenta blocks the birth canal)
abruptio placenta (when the placenta detaches from the uterus before the baby is born)
prolapsed umbilical cord (when the umbilical cord precedes the baby through the birth canal)
abnormal presentation of the baby, including breech (buttocks first), face (chin first), brow (eyebrow first) or footling (feet first) or transverse lie (lying crosswise)
shoulder dystocia (when one shoulder lodges against the pubic bone and gets caught in the birth canal)
fetal distress, which may be indicated by the fetal heart rate or amniotic fluid stained with meconium (the baby's first stool)
postmaturity (when the placenta begins to stop functioning normally in a pregnancy that continues beyond 42 weeks)
Many complications can be prevented or treated with proper obstetrical care throughout the pregnancy. As soon as you suspect you're pregnant, establish yourself with a doctor. Remember to keep all of your appointments. If you notice any unusual symptoms, call your doctor right away.

To help you prepare for childbirth, consider attending childbirth education classes. They're typically offered through hospitals or local childbirth associations. Ask your doctor for details.