The puerperium is the period that begins after the delivery of the placenta and lasts until the reproductive organs have returned to approximately their prepregnant condition. The puerperium is usually considered to last 6 weeks.
Postpartum shivering is observed in 25 to 50 percent of women after normal delivery. The pathogenesis of postpartum chills is not clear. No treatment is necessary other than supportive care. When shivering is anesthesia related, it can be treated pharmacologically.
After the delivery of the placenta and membranes, contractions reduce the size of the uterus so that it can be felt as a hard, globular mass lying just below the umbilicus. Contraction of interlacing myometrial muscle bundles constricts the intramyometrial vessels, impeding blood flow and preventing postpartum hemorrhage. Moreover, large vessels at the placental site thrombose, a secondary hemostatic mechanism for preventing blood loss at this site.
The uterus weighs 1000 to 1200 g immediately after delivery. It rapidly falls to 500 g by 7 days, disappears into the pelvis by 2 weeks, and is back to its nonpregnant weight of 50 to 70 g by 6 weeks. This reduction is the result mainly of a decrease in the size of the myometrial cells rather than of their number.
Involution of the placental site also takes up to 6 weeks. Immediately after delivery, the placental site is elevated, irregular, and friable and is composed of thrombosed vascular sinusoids. These undergo gradual hyalinization. Most of the decidua basalis is shed over a period of weeks and is replaced by regenerating endometrium. Failure of normal involution of the placental site may lead to late postpartum hemorrhage.
The basal portion of the decidua remains after delivery of the placenta. The decidua divides in two layers: the superficial layer and the deep layer. The deep layer, which contains some endometrial glands, regenerates new endometrium. Restoration of the endometrial cavity is rapid and is complete in 16 to 21 days. The superficial layer of decidua surrounding the placental site becomes necrotic and is sloughed off during the first 5 to 6 days. This postpartum vaginal discharge, made up of a mixture of blood and necrotic decidua, is called “lochia.” It is red for 2 to 3 days (lochia rubra), becomes paler as the bleeding is reduced (lochia serosa), and by 7 days is yellowish-white (lochia alba). The total volume of postpartum lochial secretion is 200 to 500 mL and lasts from 3 to 6 weeks.
Regeneration of the Endometrium
The deeper part of the decidua that contains some endometrial glands remains intact and is a source of a new lining of the uterine cavity. Restoration of the endometrium is rapid; by the seventh day, it resembles the nonpregnant state and is complete by 16 to 21 days.
Immediately after delivery, the cervix is floppy and ragged with several small tears and bleeding points that are insignificant. The cervical os closes gradually. It admits two to three fingers for the first 4 to 7 days and by the end of 10 to 14 days is barely dilated.
The glandular hypertrophy and hyperplasia of pregnancy regresses gradually, and this process is complete by about 6 weeks. The squamous epithelium that was lacerated during delivery heals and undergoes rapid re-epithelialization, but not all cervices regain their prepregnant appearance. Persistence of glandular epithelium on the exocervix is described as a cervical ectropion.
After delivery, the vagina is a spacious, smooth-walled cavity with poor tone. Gradually, the vascularity and edema decrease, and by 4 weeks, the rugae reappear, although they are less prominent than in nulliparas. The vaginal epithelium appears atrophic for some time (longer in lactating women) but looks normal by 6 to 10 weeks.
Lacerations of the lower vagina and perineum heal gradually. Perineal care is a matter of hygiene. Showers and washing with soap and water are sufficient for most patients. Hot sitz baths reduce perineal tenderness and promote healing of episiotomy and lacerations. The suggestion has been put forward that ice baths, by causing vasoconstriction, reduce edema, inflammation, and bleeding. They may also decrease the excitability of nerve endings, relieving muscular irritability and spasm. This may relieve pain more effectively and for a longer period than hot baths. The drawback to this treatment is that the patient has to endure the sensation of cold, burning, and aching until the numbness and analgesia supervene.
The cells decrease in size and number. Two weeks after delivery, the tubal epithelium is similar to that seen in menopause, with atrophy and deciliation. After 6 to 8 weeks, the normal structure has been regained.
The puerperal period is one of relative infertility, especially for women who are lactating. In nonlactating mothers, initial postpartum ovulation can occur within 6 weeks. In women, who exclusively breastfeed without supplementation, ovulation is usually reliably delayed by at least 6 months. The incidence of conception in this situation is only 2 percent, but additional contraception should be considered, depending on individual circumstances.
The occurrence of the first menstruation varies, but most nonlactating women have menstruated by 12 weeks after delivery. The return of menstruation is usually delayed in lactating women. Menses within the first 6 weeks are rarely ovulatory.
In the early puerperium, the breasts undergo marked changes. Between the second and fourth day, the breasts become engorged with increased vascularity and areolar pigmentation. There is enlargement of the lobules resulting from an increase in the number and size of the alveoli. At this time, lactation begins, controlled by various hormones. The production of milk occurs spontaneously but is enhanced by suckling. Once lactation is established, the most important stimulus for the continuation of the production of milk is suckling. A message is sent via the nervous system to the hypothalamus, and there is an increase in the production and release of oxytocin. Oxytocin stimulates the myoepithelial cells of the alveoli of the breasts to contract, causing milk to be transported to, and sometimes through, the nipple. This is the “letdown” reflex.
Some mothers are unable to breastfeed their infants for a variety of reasons, including insufficient milk, inverted nipples, diseases of the breast, or the need to take drugs that may be excreted in the milk and effect the baby. Others simply choose not to.
In 60 to 70 percent of women, who do not wish to breastfeed, lactation can be suppressed by the use of a tight bra and the avoidance of stimulation of the nipple. Pharmacologic suppression is no longer advised because of a high incidence of rebound phenomenon.
The cardiac output increases during the first and second stages of labor. It rises even higher immediately after the birth as the reduction in uterine size squeezes an additional amount of fluid into the circulation. After a short interval, the cardiac output decreases to about 40 percent above the prelabor levels and returns to normal after 2 to 3 weeks. The decrease in heart rate is partly responsible for the reduced cardiac output. Changes in blood volume result from loss of blood at delivery and from the mobilization and excretion of extravascular fluid.
The dilatation that takes place in the urinary collecting system during pregnancy does not return to normal for more than 6 weeks. The combination of loss of tone, trauma to the bladder during delivery, and anesthesia (especially of the conduction variety) may lead to retention of urine, necessitating catheterization.
Mobility of the intestines, which is decreased during pregnancy, gradually returns to normal. The use of excessive analgesia may delay this process. Laxatives or an enema may be required.