Labor is a series of rhythmic contractions of the uterus that get steadily stronger. They cause the cervix (the opening of the uterus) to open up.
No one knows what causes labor to start. It usually begins within two weeks before or two weeks after a woman's estimated due date. If it is the first time that a woman is having a baby, labor usually lasts between 12 and 14 hours; in pregnancies that follow, labor is often shorter, averaging between six and eight hours.
A woman should talk to her doctor about what the signs of the start of labor are. These include:
- Back pain
- The appearance of bloody show (the discharge of a small amount of blood and mucous from the cervix), which may happen as early as three days before labor starts
- Irregular contractions of varying intensity. The contractions get more regular, are longer, stronger and happen more often as labor continues.
- Breaking of the membranes of the amniotic sac (which lines the woman's uterus and contains the baby during pregnancy). This causes amniotic fluid to leak through the cervix and vagina. When this happens a woman should call her doctor right away. Between 80 and 90% of women with ruptured membranes go into labor within 24 hours. If this doesn't happen and the baby is due, labor is induced to reduce the risk of infection.
At such a special time in their lives, many women prefer to have their babies in a less institutional environment. Having a baby at home is not recommended because of the possibility of unexpected complications that can occur.
In response to women's desire to have a more home-like birthing experience, special maternity suites are available.
Having the baby's father or other support person during labor is helpful. The moral support, encouragement and expressions of affection make the process of labor less frightening and anxious. Sharing the experience of labor, seeing their own child for the first time and the sound of its crying tends to create strong bonds between the parents and between the parents and child.
When a woman in labor arrives at the hospital, her blood pressure, heart and breathing rates, temperature and weight are recorded. She will be checked for signs of swelling. Blood and urine tests will be given. A physical examination will be done.
The doctor will estimate the size, position and orientation of the baby. He or she will check for the baby's heart sounds. Additionally, the doctor will take note of how long, how intense and how often the contractions are coming.
If labor is active and the baby is due, a labor-and-delivery nurse or a doctor will do an internal examination with a gloved hand to evaluate how the labor is going. This exam maybe delayed if there is heavy bleeding.
If the waters have broken (the amniotic sac's membranes have broken), the doctor or nurse will look for any greenish discoloration that might be a sign of fetal distress.
The woman in labor will be admitted to the labor suite for regular monitoring until delivery. Monitoring will include:
- How much the woman's cervix has opened up, which is measured in centimeters as the diameter of a circle
- How much thinning (effacement) of the cervix has occurred, which is measured as a percentage
- Where the baby is inside the woman's pelvis. This is described in centimeters above or below the top edges of the pelvic bones.
- How the baby is oriented toward the cervix -- head first (vertex), feet first (breech), shoulder, etc.
- How the baby is aligned inside the pelvis -- what direction the baby faces
- The mother's vital signs
- The baby's vital signs
While in the delivery suite, a woman will be given little to eat or drink to avoid vomiting or choking during delivery. An intravenous infusion may be started to prevent dehydration during labor. This also provides an immediate way to provide drugs or blood in an emergency.
Drugs to relieve pain may be given during labor if needed. As little as possible is given to avoid depressing the newborn's breathing. Having had childbirth classes before going into labor helps reduce anxiety and the need for pain relievers.
The first stage of labor goes from the beginning of labor until the cervix is fully open (about 10 centimeters). As this stage continues, a woman may begin to feel the urge to bear down as the baby drops lower in her pelvis. She should avoid doing this, however, until her cervix is fully open to prevent tearing the cervix and using up energy.
The second stage goes from full dilation (opening) of the cervix to delivery of the baby. This stage usually lasts about two hours in a woman who has never had a baby before and one hour in a women has previously had children. During this time, the woman must add to the contractions her body is doing naturally by bearing down to push the baby toward delivery.
During labor, both the mother's heart rate and blood pressure and the baby's heart rate should be checked continuously by electronic monitor.
It is particularly important to monitor the baby's heart rate during labor and delivery. Between a third to half of the babies who develop fetal distress or die during delivery do so without any significant signs beforehand. Electronically monitoring the baby can help pinpoint fetal distress before it becomes dire.
Pain relief may be needed during labor. It must be carefully done to assure a safe delivery for both baby and mother. Better preparation for childbirth and training in giving birth without anesthesia has reduced the need for this except in cases where it is necessary to use forceps, deliver a breech baby or twins or to have a cesarean section.
The usual forms of anesthesia given during labor are:
- Pudendal block, in which a local anesthetic is injected through the vaginal wall. This is useful for uncomplicated deliveries and ones where the mother wants to push during delivery.
- Regional anesthesia. The most often used for labor and delivery is an injection of a local anesthetic in the back.
- General anesthesia. This is not used for routine deliveries because it can depress both the mother's and the fetus's vital signs.
The next phase of pregnancy is delivery.
