Labor proceeds in three stages (see Figure 2-13). In the first stage of labor, the uterine contractions initially occur around every 8 to 10 minutes and last about 30 seconds. As labor proceeds, the contractions occur more frequently and last longer. Toward the end of labor, the contractions may occur every 2 minutes and last almost 2 minutes. As the first stage of labor ends, the contractions reach their greatest intensity, a period known as transition. The mother's cervix fully opens, eventually expanding enough (usually to around 10 cm) to allow the baby's head to pass through.
• This first stage of labor is the longest. Its duration varies depending on the mother's age, race, ethnicity, number of prior pregnancies, and other factors. Typically, labor takes 16 to 24 hours for firstborn children, but there are wide variations. Labor becomes shorter for subsequent children.
• During the second stage of labor, which typically lasts around 90 minutes, the baby's head proceeds further with each contraction, increasing the size of the vaginal opening. Because the area between the vagina and rectum must stretch, an incision called an episiotomy is some- times made to increase the size of the opening of the vagina. However, this practice is now seen as potentially harmful, and the number of episiotomies has fallen drastically in the last decade (Goldberg et al., 2002; Graham et al, 2005; Dudding, Vaizey, & Kamm, 2008).
• The second stage of labor ends when the baby has completely left the mother's body. Finally, in the third stage of labor the child's umbilical cord (still attached to the neonate) and the placenta are expelled from the mother. This stage is the quickest and easiest, taking just a few minutes.
• The nature of a woman's reactions to labor reflects, in part, cultural factors. Although there is no evidence that the physiological aspects of labor differ among women of different cul- tures, expectations about labor and interpretations of its pain do vary significantly from one culture to another (Callister et al., 2003; Fisher, Hauck, & Fenwick, 2006). For instance, there is a kernel of truth to popular stories of women in some societies putting down their tools, giving birth, and immediately returning to work with their neonates on their backs. Accounts of the !Kung people in Africa describe women giving birth without much ado—or assistance—and quickly recovering. On the other hand, many societies regard childbirth as dangerous or even as essentially an illness.