Maternal Physiologic Changes
• Describe the anatomic and physiologic changes that occur during the postpartum period.
• Identify characteristics of uterine involution and lochial flow, and describe ways to measure them.
• List expected values for vital signs, deviations from normal findings, and probable causes of the deviations.
Painful uterine cramps that occur intermittently for approximately 2 or 3 days after birth and that result from contractile efforts of the uterus to return to its normal involuted condition
Thin, yellowish to white, vaginal discharge that follows lochia serosa on approximately the tenth day after birth and that may last from 2 to 6 weeks postpartum
Serous, pinkish brown, watery vaginal discharge that follows lochia rubra until approximately the tenth day after birth
Period between the birth of the newborn and the return of the reproductive organs to their normal nonpregnant state; fourth trimester of pregnancy
Web Resources
Additional related content can be found on the companion website at 
http://evolve.elsevier.com/Lowdermilk/Maternity/
T he postpartum period is the interval between the birth of the newborn and the return of the reproductive organs to their normal nonpregnant state. This period is sometimes called the puerperium, or fourth trimester of pregnancy. Although the puerperium has traditionally been considered as lasting 6 weeks, this time frame varies among women. The distinct physiologic changes that occur as the processes of pregnancy are reversed are normal. To provide care during the recovery period that is beneficial to the mother, her infant, and her family, the nurse must synthesize knowledge of maternal anatomy and physiology of the recovery period, the newborn’s physical and behavioral characteristics, infant care activities, and family response to the birth of the infant. This chapter focuses on anatomic and physiologic changes that occur in the mother during the postpartum period.
Reproductive System and Associated Structures 
Uterus
Involution process
The return of the uterus to a nonpregnant state after birth is known as involution. This process begins immediately after expulsion of the placenta with contraction of the uterine smooth muscle.
At the end of the third stage of labor the uterus is in the midline, approximately 2 cm below the level of the umbilicus, with the fundus resting on the sacral promontory. At this time the uterus weighs approximately 1000 g.
Within 12 hours the fundus rises to the level of the umbilicus, or slightly above or below (Fig. 13-1). Thereafter the fundus descends approximately 1 cm every day. By 1 week after birth the fundus is located 4 to 5 fingerbreadths below the umbilicus. The uterus should not be palpable abdominally after 2 weeks and should have returned to its nonpregnant location by 6 weeks after birth (Blackburn, 2007).
Spanish Guidelines: Postpartum Physical ExaminationThe uterus, which at full term weighs approximately 11 times its prepregnancy weight, involutes to approximately 500 g by 1 week after birth and to 350 g by 2 weeks after birth. At 6 weeks, it weighs 60 to 80 g (see Fig. 13-1).
Subinvolution is the failure of the uterus to return to a nonpregnant state. The most common causes of subinvolution are retained placental fragments and infection (see Chapter 23).
Contractions
Postpartum hemostasis is achieved primarily by compression of intramyometrial blood vessels as the uterine muscle contracts rather than by platelet aggregation and clot formation. The hormone oxytocin, released from the pituitary gland, strengthens and coordinates these uterine contractions, which compress blood vessels and promote hemostasis. During the first 1 to 2 postpartum hours, uterine contractions may decrease in intensity and become uncoordinated. Because the uterus must remain firm and well contracted, exogenous oxytocin (Pitocin) is usually administered intravenously or intramuscularly immediately after expulsion of the placenta. Women who plan to breastfeed should also be encouraged to put the baby to the breast immediately after birth because suckling stimulates oxytocin release.
Afterpains
In first-time mothers, uterine tone is good, the fundus generally remains firm, and the mother usually perceives only mild uterine cramping. Periodic relaxation and vigorous contraction are more common in subsequent pregnancies and may cause uncomfortable cramping called afterpains (afterbirth pains) that persist throughout the early puerperium. Afterpains are more noticeable after births in which the uterus was overdistended (e.g., large baby, multifetal gestation, polyhydramnios). Breastfeeding and exogenous oxytocic medication usually intensify these afterpains because both stimulate uterine contractions.
Placental site
Immediately after the placenta and membranes are expelled, vascular constriction and thromboses reduce the placental site to an irregular nodular and elevated area. Upward growth of the endometrium causes sloughing of necrotic tissue and prevents the scar formation that is characteristic of normal wound healing. This unique healing process enables the endometrium to resume its usual cycle of changes and to permit implantation and placentation in future pregnancies. Endometrial regeneration is completed by postpartum day 16, except at the placental site. Regeneration at the placental site occurs gradually and is not usually complete until 6 weeks after birth (Blackburn, 2007).
Lochia
Post-childbirth uterine discharge, commonly called lochia, is initially bright red (lochia rubra) and may contain small clots. For the first 2 hours after birth the amount of uterine discharge should be approximately that of a heavy menstrual period. After that time the lochial flow should steadily decrease.
Lochia rubra consists mainly of blood and decidual and trophoblastic debris. The flow pales, becoming pink or brown (lochia serosa) after 3 to 4 days. Lochia serosa consists of old blood, serum, leukocytes, and tissue debris. The median duration for lochia serosa discharge is 22 to 27 days (Katz, 2007). In most women, approximately 10 days after childbirth the drainage becomes yellow to white (lochia alba). Lochia alba consists primarily of leukocytes and decidual cells but also contains epithelial cells, mucus, serum, and bacteria. Lochia alba may last until 6 weeks after birth (Blackburn, 2007).
If the woman receives an oxytocic medication, the flow of lochia is often scant until the effects of the medication wear off. The amount of lochia is typically smaller after cesarean births. Flow of lochia usually increases with ambulation and breastfeeding. Lochia tends to pool in the vagina when the woman is lying in bed; on standing the woman may experience a gush of blood. This gush should not be confused with hemorrhage.
Persistence of lochia rubra early in the postpartum period suggests continued bleeding as a result of retained fragments of the placenta or membranes. Recurrence of bleeding approximately 7 to 14 days after birth is from the healing placental site. Approximately 10% to 15% of women will still be experiencing normal lochia serosa discharge at the 6-week postpartum examination (Katz, 2007). In the majority of women, however, a continued flow of lochia serosa or lochia alba by 3 to 4 weeks after birth may indicate endometritis, particularly if fever, pain, or abdominal tenderness is associated with the discharge. Lochia should smell similar to normal menstrual flow; an offensive odor usually indicates infection.
Not all postpartal vaginal bleeding is lochia; vaginal bleeding after birth may be a result of unrepaired vaginal or cervical lacerations. Table 13-1 distinguishes between lochial and nonlochial bleeding.
TABLE 13-1
Lochial and Nonlochial Bleeding
| LOCHIAL BLEEDING | NONLOCHIAL BLEEDING |
| Lochia usually trickles from the vaginal opening. The steady flow increases as the uterus contracts. | If the bloody discharge spurts from the vagina, damage to a blood vessel may have occurred during birth. If so, some of the bleeding is not just normal lochial flow. |
| A gush of lochia may result as the uterus is massaged. If the lochia is dark in color, it has been pooled in the relaxed vagina, and the amount soon lessens to a trickle of bright red lochia (in the early puerperium). | If the amount of bleeding continues to be excessive and bright red, a vaginal or cervical tear may be the source. |
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