Excerpt from Normal and Abnormal Puerperium

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Puerperium is defined as the time from the delivery of the placenta through the first few weeks after the delivery. This period is usually considered to be 6 weeks in duration. By 6 weeks after delivery, most of the changes of pregnancy, labor, and delivery have resolved and the body has reverted to the nonpregnant state.

An overview of the relevant anatomy and physiology in the postpartum period follows.

Uterus

The pregnant term uterus (not including baby, placenta, fluids, etc) weighs approximately 1000 grams. The uterus recedes to a nonpregnant state, with a weight of 50-100 grams, during the 6 weeks after delivery.

Immediately after delivery, the uterus can be palpated at or near the umbilicus. Most of the reduction in size and weight occurs in the first 2 weeks, at which time the uterus has shrunk enough to be located in the true pelvis.

The endometrial lining rapidly regenerates, so that by the seventh day the endometrial glands are already evident. By the 16th day, the endometrium is restored throughout the uterus, except at the placental site.

The placental site undergoes a series of changes in the postpartum period. Immediately after delivery, the contractions of the arterial smooth muscle and compression of the vessels by contraction of the myometrium result in hemostasis. The size of the placental bed decreases by half, and the changes in the placental bed result in the quantity and quality of the lochia that is experienced.

Postpartum, a large amount of red blood initially flows from the uterus as the contraction phase rapidly occurs. The volume rapidly decreases. The duration of this discharge (lochia), known as lochia rubra, is variable. The red discharge changes to brownish red, with a more watery consistency, which is known as lochia serosa. Over a period of weeks, the discharge continues to decrease in amount and color and changes to yellow, which is known as lochia alba. The period of time the lochia can last varies, although it averages approximately 5 weeks, with a waxing and waning amount of flow and color.

Each woman has her own pattern, with the various phases of the lochia lasting for different lengths of time. Fifteen percent of women have lochia at 6 weeks postpartum. Often, women experience an increase in the amount of bleeding at 7-14 days secondary to the sloughing of the eschar on the placental site.

Cervix

The cervix also begins to rapidly revert to a nonpregnant state, but it never returns to the nulliparous state. By the end of the first week, the external os is closed to the extent that a finger could not be easily introduced.

Vagina

The vagina, which was distended to accommodate the baby, shrinks to a nonpregnant state, but it does not completely return to its prepregnant size. Resolution of the increased vascularity and edema occurs by 3 weeks, and the rugae of the vagina begin to reappear in women who are not breastfeeding. At this time, the vaginal epithelium appears atrophic on smear. This is restored by weeks 6-10; however, it is further delayed in breastfeeding mothers because of persistently decreased estrogen levels.

Perineum

The perineum has been stretched and traumatized, and sometimes torn or cut, during the process of labor and delivery. The swollen and engorged vulva rapidly resolves, and swelling and engorgement are completely gone within 1-2 weeks. Most of the muscle tone is regained by 6 weeks, with more improvement over the following few months. The muscle tone may or may not return to normal, depending on the extent of injury.

Abdominal wall

The abdominal wall remains soft and poorly toned for many weeks. The return to a prepregnant state depends greatly on exercise.

Ovaries

The resumption of normal function by the ovaries is highly variable and is greatly influenced by breastfeeding the infant. The woman who breastfeeds her infant has a longer period of amenorrhea and anovulation than the mother who chooses to bottle-feed. The mother who does not breastfeed may ovulate as early as 27 days after delivery. Most women have a menstrual period by 12 weeks; the mean time to first menses is 7-9 weeks.

In the breastfeeding woman, the resumption of menses is highly variable and depends on a number of factors, including how much and how often the baby is fed and whether the baby's food is supplemented with formula. The delay in the return to normal ovarian function in the lactating mother is caused by the suppression of ovulation due to the elevation in prolactin. Half to three fourths of women who breastfeed return to periods within 36 weeks of delivery.

Breasts

The changes to the breasts that prepare the body for breastfeeding occur throughout pregnancy. Lactation can occur by 16 weeks' gestation. Lactogenesis is initially triggered by the delivery of the placenta, which results in falling levels of estrogen and progesterone, with the continued presence of prolactin. If the mother is not breastfeeding, the prolactin levels decrease and return to normal within 2-3 weeks.

The colostrum is the liquid that is initially released by the breasts during the first 2-4 days after delivery. High in protein content, this liquid is very protective for the newborn. The colostrum, which the baby receives in the first few days postpartum, is already present in the breasts, and suckling by the newborn triggers its release. The process, which begins as an endocrine process, switches to an autocrine process; the removal of milk from the breast stimulates more milk production. Over the first 7 days, the milk matures and contains all necessary nutrients in the neonatal period. The milk continues to change throughout the period of breastfeeding to meet the changing demands of the baby.

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