Birth

Labor progresses through three stages: dilation, or "the opening," expulsion, and placental. The first stage, dilation, can last anywhere from two hours to sixteen hours or more. At first, each contraction is thirty to forty-five seconds in duration and occurs about every fifteen to twenty minutes. The contractions are involuntary and the woman cannot start them or stop them at will or make them come faster or slower. Their function is to dilate the cervix until it is wide enough to let the baby through—usually about four inches (ten centimeters). In the course of the first stage of labor the contractions increase in frequency until they are only a minute or two apart. Each contraction itself also becomes longer and, toward the end of the first stage, may last ninety seconds.

At the end of the first stage there may be a series of very intense contractions; during this time the cervix has been stretched around the baby's head. The woman may feel ready to give up, but this phase, known as transition, is soon over. It rarely lasts more than half an hour and is often much shorter. In expulsion, the second stage of labor, the involuntary contractions continue to be long in duration and closely spaced, but now the woman has a strong urge to bear down with her abdominal muscles. At each new contraction she pushes down with all her strength as the baby's scalp comes into view, only to disappear again when the contraction ends. This is known as crowning. With each contraction more and more of the baby's head can be seen. At this point in labor, some obstetricians may perform an episiotomy (making a small slit in the skin outside the vagina toward the anus) to prevent this tissue from tearing. When the baby's head comes out as far as its widest diameter, it stays out, and in a short time it is free. The head may be molded (elongated in shape as a result of its passage through the cervix), but the soft skull bones that have been squeezed together soon recover their normal shape.

Some babies will give their first cry at this point. With the next contractions the shoulders emerge, and the rest of the body slips out easily. The feelings of both parents at this time are almost impossible to put into words: elation, exhaustion, and great feelings of tenderness and caring.

It was once the practice for the doctor to hold the baby up by the feet immediately following delivery to allow fluid and mucus to escape from the baby's mouth and nose, so that the infant could start breathing, usually with a gasp and a cry. Today it is more usual to aspirate the mucus from the baby's mouth and nose by suction as soon as the head is delivered. This gives the baby a slight head start on independent breathing.

As soon as delivery is complete, the umbilical cord is clamped and cut. The baby is then wrapped in a receiving blanket, and someone performs a variety of procedures that vary from hospital to hospital. Typically, drops of silver nitrate are placed in the baby's eyes to prevent infection, both mother and baby are given plastic identification bracelets, and fingerprints of the mother and sometimes footprints of the baby are taken.

At this time the neonate's general state of health is evaluated using the APGAR scoring system. At one, five, and ten minutes after birth the baby is given a score of 0, 1, or 2 on Activity (muscle), Pulse (or heart rate), Grimace (or reflex action), Appearance (color), and Respiration (breathing). This test provides very general information on whether the baby's life-sustaining functions appear normal and what kinds of potentially dangerous problems may be present. The majority of children score between 5 and 10, and 90 percent have a score of 7 or better; there is no reason for concern unless the score is below 5.

During the third or placental stage, the afterbirth (the placenta and cord) is expelled from the uterus. Labor is now completed.

The length of the entire process varies greatly, as does the actual experience of labor. Fifteen hours is an average figure for the duration of birth from the first contraction to the expulsion of the afterbirth for a first birth. But this average covers a spectrum of labor as long as twenty-four hours and as short as three hours or less. Labor is usually longer for first babies than for later ones, and longer for boys than girls. Two reasons for a longer first labor might be the easier adaptation of the woman's body to the process and the reduced amount of anxiety present in subsequent births.