Normal Puerperium Physiology Duration Ppt

[Laura N Gerard]

There are particular risks associated with the puerperal period, especially infection, hemorrhage and psychosis, which speaks to the need for continued healthcare, education and help, even when pregnancy has ended with the delivery of a healthy baby. Our goal is to give an overview of the physiological puerperal changes, and highlight any new understandings. We first discuss changes to the reproductive tract and other organs, and then the cardiovascular and endocrine systems. Maternal physical and mental well-being are then discussed under complications of the puerperium, before ending with a section on lactation.

If we are impressed at how much the uterus has grown during the 9 months of pregnancy, we should be even more impressed with how quickly it reverses this growth. The uterus decreases from a weight of around 1 kg to less than 100 g. The uterus returns to around its pre-pregnant state in just 6 weeks. Despite this, the turnover of muscle proteins, connective tissue and cellular remodeling occurring during involution is relatively under-appreciated and under-researched, which perhaps can be said of the whole puerperium, compared with pregnancy. Much has been made of how to assess the rate of involution by palpation and tape measure to determine the distance between the symphysis pubis and uterine fundus. Deviation from accepted normal values could indicate an abnormality and the need for clinical investigation. Studies over the past 20 years or so have indicated that there is so much normal variation between women, and error in the measurements, that these manual measurements of involution are rarely worth doing..4,5 Sonographic data are more reliable, but not warranted for routine use. Palpation, however, showing an increase in fundal height needs further evaluation. Delayed involution may be a sign of retained products of conception or endometritis, or a high uterus due to pelvic hematoma or abscess.

The reduction in muscle mass and fiber size in involution, is not just stimulated by the large changes in the hormones that were supporting pregnancy (see below) but also the loss of mechanical stimulation, stretch.6 There is catabolism of the muscle as its mass reduces, and the extracellular matrix is remodeled by metalloproteinases. Coordinated apoptosis and proliferation results in the myometrium returning to its non-pregnant state.

The repair of the cervix during the puerperium is vital to stop infection and hemorrhage. Its remodeling and return to a rigid non-pregnant state from its flaccid postdelivery state, is vital to future term pregnancies, and involves physiological, biochemical and biophysical changes. The internal os of the cervix should have closed by second week postpartum. The external os may remain somewhat open for many weeks.

Given the extensive collagenous composition of the cervix, it is metalloproteinases and collagenases, and then extracellular matrix protein synthesis, along with cells of the immune and inflammation systems, that play the predominant role in this reconstruction of the cervix.8 Interestingly, a recent proteomic analysis of mouse postpartum cervix, identified four pathways that were significantly differentially upregulated during remodeling and warrant further investigation: intermediate filaments, actin-binding proteins, hypoxia-induced proteins, and proteins involved in immune modulation and/or wound healing.9

The vagina and vulva will initially be edematous, and enlarged but return to their usual state over the first few weeks of the puerperium. The vaginal walls will weaken slightly with each pregnancy, contributing to the age-related risk of genital prolapse.

Leak of urine often accompanies laughing, straining or coughing in the puerperal woman (stress incontinence), but this will naturally resolve in most women. It is assumed to occur due to the stretching of the base of the bladder during both pregnancy and delivery. Pelvic floor exercises will help. Specialist help should be provided if the problem persists. Women should also know that pain or burning on micturition can be signs of a urinary infection in the bladder.

Although gastrointestinal symptoms are common postnatally, most are mild and resolve spontaneously. The new mother may experience thirst, hemorrhoids, hunger, flatulence or constipation, but all pass. In some cases stool softeners and topical anesthetic may be helpful. The most serious condition at this time and beyond is fecal incontinence. The muscles and nerves in the pelvic floor that control bowel movements and the anal sphincter will have been stretched and perhaps damaged during delivery. It is also the case that where forceps or vacuum delivery modes have been used, or a significant tear extends backwards, damage to nerves and muscle can occur. Although embarrassing, fecal incontinence usually resolves after several months, but needs specialist attention if it persists. Cases which do not resolve may require surgical repair.

The skin, hair, and nails rapidly reverse any changes that occurred in pregnancy. The dark pigmentation that occurs in the vulva, abdominal wall and face in some women, passes. Any edema of pregnancy is quickly dissipated. Stretch marks (striae gravidarum), become less apparent as the puerperium progresses. Most women experience hair loss over the first few months postpartum, which although potentially upsetting, is only restoring growth to non-pregnant levels. The loosening of ligaments and muscles, especially the diastasis recti, that has occurred with pregnancy, gradually reverse in the puerperium. Exercise and sporting activity should be reintroduced during the early postpartum period. This may be within a week following a normal vaginal delivery but delayed by a few weeks following a cesarean section delivery. The American College of Obstetricians and Gynecologists advises postpartum women should get at least 150 minutes of moderate-intensity aerobic activity every week.12 The general benefits of exercise on health and well-being underlie this advice, especially as a way to help increase mood, lose weight and strengthen muscle.13,14

Although respiratory problems may be common in pregnancy, the respiratory system is little affected by the puerperium. Abnormal breathing patterns should alert clinicians to postpartum complications, such as infection.

Parturition is accompanied by a large amount of oxytocin secretion from the posterior pituitary. In addition to its peripheral roles in myometrial contractility during labor, and milk ejection during lactation, oxytocin has a critical central role in the development of maternal behavior: attachment and bond formation.17 Both animal and human studies point to the role of oxytocin in the initiation of maternal behavior. There is recent suggestion that administration of exogenous oxytocin (Pitocin), as a means to augment labors, is negatively correlated with oxytocin release in breastfeeding mothers and a difficulty with suckling behavior in newborn infants.18,19

Significant changes in cardiovascular parameters occur in the puerperium and beyond. Major adaptations to the maternal cardiovascular system occur during pregnancy, which are necessary to ensure adequate blood supply to the placenta and fetus. By the third trimester of pregnancy, heart rate, stroke volume and cardiac output are increased; there is an increased plasma volume and decreased peripheral vascular resistance. Table 1 demonstrates that significant changes occur to these parameters immediately after parturition. While much of the cardiovascular system has returned to normal by 6 weeks after birth, cardiac output does not normalize until 24 weeks after birth, and peripheral vascular resistance remains elevated and is still higher than normal at 6 weeks.

There is considerable variation in the scientific literature regarding the extent and time courses of some of these hemodynamic changes (particularly in relation to stroke volume and cardiac output). Much of the variation is related to the posture of the mother when measurements were made,27 the use of invasive techniques (that have subsequently been superseded by more reliable, non-invasive techniques such as Doppler echocardiography) and whether non-pregnant, pre-conception or postpartum values are used for the control/reference group. Recent meta-analyses and comprehensive reviews can help clarify these data.28,29,30

Maternal blood in the puerperium is in a hypercoagulable state, putting mothers at risk of thromboembolism. Multiple changes occur to the coagulation system during pregnancy (Table 1). Levels of clotting factors are increased (fibrinogen, factor VII, VIII, IX, X and von Willebrand factor) and the natural anticoagulants are reduced (protein S and tissue plasminogen activator).34,35 All these aid the functioning of the placenta and prevent postpartum hemorrhage. In early puerperium, the blood remains in a hypercoagulable state and therefore mothers are still at an increased risk of thromboembolism (deep vein thrombosis and pulmonary embolism). Venous thromboembolism remains a leading cause of maternal death in the UK, with no decrease in mortality rates over the past 20 years.36 Indeed, as the maternity population is getting older, obesity levels rise and increasing numbers of cesarean sections carried out, the risk of thromboembolism will only increase.

As the plasma volume increases at a greater rate than red blood cell volume in pregnancy, a physiological hemodilution occurs. Conversely, decreases in plasma volume in the puerperium, lead to an elevated hematocrit.

The World Health Organization (WHO) now recommends exclusive breast feeding for 6 months, as there is increasing evidence for short- and long-term health benefits. However, recent numbers indicate that only 40% of mothers worldwide attain this goal (WHO and Unicef, 2017)52.

Preparation for lactation occurs during puberty and pregnancy, well before puerperium and the initial latch of the newborn infant. It is important to appreciate the structure and cellular components of the lactating breast in order to fully understand the physiology of lactation (see Figure 2). During puberty, increasing estrogen and progesterone levels stimulate development of new alveolar buds from which milk-secreting mammary gland lobules will evolve. During pregnancy, the volume of breast tissue increases and formation of new alveolar-lobular structures continues alongside further maturation of the milk-producing apparatus. Estrogen, progesterone and prolactin are necessary for such development in pregnancy; however, other factors including placental lactogen and growth hormone also play a role. Little or no milk is produced during pregnancy because high levels of progesterone and estrogen block the secretory activity of the cells in the alveoli. During labor and lactation, further growth and differentiation occurs increasing the glandular component of the breast.

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