Maternal Changes During the Puerperium
Maternal physiological changes during the puerperium occur across multiple systems of the body, with the most notable changes occurring in the reproductive system.
Changes in the Reproductive System
Uterus
The uterus undergoes the most significant changes during the puerperium. The process of the uterus returning to its pre-pregnancy state after placental delivery is called uterine involution, which typically takes about 6 weeks. The major changes include contraction and retraction of uterine myofibers and regeneration of the endometrium, along with changes in uterine blood vessels and recovery of the lower uterine segment and cervix.
Contraction and Retraction of Uterine Myofibers
Uterine involution involves a reduction not in the number of muscle cells but in the size of muscle cells due to the breakdown and discharge of proteins in the cytoplasm. These proteins and their metabolites are excreted via the kidneys. Following placental delivery, the uterus gradually shrinks to the size of a 12-week pregnant uterus by the first postpartum week and returns to its pre-pregnancy size by the sixth week. Uterine weight also reduces from approximately 1,000 g at the end of labor to 500 g by the first week postpartum, 300 g by the second week, and 50–70 g by the sixth week.
Regeneration of the Endometrium
After separation and expulsion of the placenta and fetal membranes from the spongy layer of the decidua, the remaining decidua is divided into two layers. The superficial layer undergoes degeneration, necrosis, and shedding, forming a component of lochia that is discharged through the vagina. Meanwhile, the basal layer of the endometrium adjacent to the myometrium gradually regenerates a new functional layer. By the third postpartum week, the uterine cavity is completely covered with new endometrium except at the site of placental attachment, which requires up to 6 weeks for complete repair.
Changes in Uterine Blood Vessels
Following placental delivery, the placental attachment site reduces to about half its original size. Uterine involution compresses the open spiral arteries and venous sinuses, and thrombosis gradually forms in the vessels within hours, leading to reduced and eventually stopped bleeding. However, late postpartum hemorrhage may occur if thrombi at the placental attachment site detach due to poor involution during endometrial repair.
Recovery of the Lower Uterine Segment and Cervix
Muscular contractions in the lower uterine segment bring about its gradual recovery to the non-pregnant uterine isthmus. After placental delivery, the external cervical os becomes annular, resembling a cuff. By 2–3 days postpartum, the cervical os can admit two fingers. By the first postpartum week, the internal os closes, and the cervical canal retracts. By the fourth postpartum week, the cervix has returned to its pre-pregnancy form. Slight lacerations of the external cervical os during delivery may result in a change from the round shape seen in nulliparous women to a transverse slit (“fish-mouth” shape) in women who have delivered vaginally.
Vagina
The vaginal canal enlarges after delivery, with the mucosa and surrounding tissues becoming edematous. Vaginal rugae reduce or disappear due to excessive stretching, resulting in laxity and decreased muscle tone of the vaginal wall. During the puerperium, vaginal muscle tone gradually recovers, and the vaginal cavity contracts. Vaginal rugae typically reappear by the third postpartum week but do not fully restore to their pre-pregnancy tightness by the end of the puerperium.
External Genitalia
Mild edema of the external genitalia occurs immediately after delivery and usually subsides within 2–3 days postpartum. In the perineal region, rich blood circulation facilitates healing of minor lacerations or episiotomy sutures, with most wounds healing by 3–4 days postpartum.
Pelvic Floor Tissues
During delivery, prolonged pressure from the presenting fetal part can result in overextension and reduced elasticity of the pelvic floor muscles and fascia, often accompanied by partial muscle fiber tearing. Heavy physical activity should be avoided during the puerperium. Postpartum rehabilitation exercises during this period may help restore the pelvic floor muscles to a state close to their pre-pregnancy condition. Severe tearing of the pelvic muscles and fascia, combined with early heavy physical activity or repeated short-interval deliveries, may result in pelvic floor tissue laxity. If recovery is incomplete, pelvic organ prolapse may occur.
Changes in the Breasts
The primary change in the breasts is milk production. During pregnancy, elevated levels of estrogen, progesterone, and human placental lactogen promote the development and growth of mammary glands, darkening of the areola, and preparation for lactation. After placental delivery, levels of estrogen, progesterone, and human placental lactogen in the maternal blood drop sharply, reducing inhibition of prolactin-releasing factor by the hypothalamus. This enables prolactin to stimulate milk secretion.
When the infant suckles on the nipple, sensory signals from the nipple are transmitted via afferent nerves to the hypothalamus, which inhibits the release of dopamine and other prolactin-inhibiting factors, resulting in pulsatile release of prolactin by the anterior pituitary, thereby promoting milk secretion. Nipple suckling also reflexively triggers the release of oxytocin by the posterior pituitary. Oxytocin induces contraction of the myoepithelial cells around the mammary alveoli, forcing milk from the alveoli and ducts into the lactiferous sinuses, where it is ejected. This process is called the milk ejection reflex. Milk stasis may occur if milk is not adequately drained during this period, leading to breast engorgement and the formation of hard masses. Conversely, underproduction of milk may result in soft and empty breasts.
Changes in the Circulatory and Hematological Systems
After placental separation, uteroplacental circulation ceases, and uterine contraction causes a large volume of blood to return to the maternal systemic circulation. Additionally, the interstitial fluid retained during pregnancy is reabsorbed. As a result, within the first 72 hours postpartum, the maternal circulating blood volume increases by 15%–25%. There is a need to remain vigilant for the potential occurrence of heart failure. Circulating blood volume typically returns to pre-pregnancy levels within 2–3 weeks postpartum.
During the early puerperium, blood remains in a hypercoagulable state, which promotes thrombus formation at the placental site to reduce postpartum bleeding. However, this also increases the risk of deep vein thrombosis and pulmonary embolism during the puerperium. Fibrinogen, thrombin, and prothrombin levels return to normal within 2–4 weeks postpartum. Hemoglobin levels rise approximately one week after delivery. Total white blood cell counts remain elevated during the early puerperium, reaching (15–30)×109/L, and normalize within 1–2 weeks. Lymphocytes slightly decrease, neutrophils increase, and platelet counts rise. The erythrocyte sedimentation rate (ESR) normalizes within 3–4 weeks after delivery.
Changes in the Digestive System
During pregnancy, gastrointestinal motility and muscle tone decrease, and gastric acid secretion is reduced. These functions gradually recover within 1–2 weeks postpartum. In the first 1–2 days postpartum, women commonly experience thirst and prefer liquid or semi-liquid diets. Reduced activity during the puerperium, diminished intestinal motility, and relaxation of the abdominal and pelvic floor muscles increase the likelihood of constipation.
Changes in the Urinary System
Urinary output increases significantly during the first postpartum week. The dilation of the renal pelvis and ureters observed during pregnancy typically resolves within 2–8 weeks postpartum. During the puerperium, especially within the first 24 hours, decreased bladder muscle tone and reduced sensitivity to bladder pressure, together with factors such as perineal pain from episiotomy or prolonged perineal pressure during labor, instrumental delivery, and regional anesthesia, can increase the likelihood of urinary retention.
Changes in the Endocrine System
Levels of estrogen and progesterone drop sharply after delivery and return to pre-pregnancy levels within the first postpartum week. Human placental lactogen becomes undetectable approximately six hours postpartum. Prolactin levels vary depending on whether the mother is breastfeeding. In lactating women, prolactin levels decrease postpartum but remain higher than in non-pregnant states. In non-lactating women, prolactin levels return to non-pregnant levels within two weeks postpartum. Human chorionic gonadotropin (hCG) typically returns to pre-pregnancy levels around 10 days postpartum.
The timing of menstruation and ovulation resumption is influenced by breastfeeding. Non-lactating women typically experience menstrual resumption within 6–10 weeks postpartum and ovulation around 10 weeks postpartum. Lactating women experience a delayed resumption of menstruation, and some women may not menstruate during the entire breastfeeding period. On average, ovulation resumes between 4–6 months postpartum in lactating mothers. For women whose menstruation resumes later postpartum, ovulation often occurs before their first menstrual period, meaning lactating mothers can conceive even without menstruation.
Changes in the Abdominal Wall
Pigment deposition observed along the midline of the lower abdomen during pregnancy gradually fades during the puerperium. Striae gravidarum, initially purplish-red in appearance, turn into silvery-white marks in primiparous women. Due to the effects of the enlarged uterus during pregnancy, some elastic fibers in the abdominal wall skin tear, and varying degrees of separation of the rectus abdominis occur. Postpartum, the abdominal wall becomes noticeably lax, and its tone typically takes 6–8 weeks to recover.
Clinical Manifestations During the Puerperium
Vital Signs
Postpartum body temperature is generally within the normal range. Slight elevation in body temperature, typically not exceeding 38°C, may occur within the first 24 hours postpartum, likely due to prolonged labor and excessive fatigue. Around 3–4 days postpartum, vascular and lymphatic engorgement of the breasts may lead to breast swelling accompanied by a rise in body temperature, known as milk fever. This usually resolves within 4–16 hours. However, it is important to rule out other causes of fever, particularly infection. Postpartum pulse rates are within the normal range. Respiration is typically deep and slow, at about 14–16 breaths per minute, due to reduced intra-abdominal pressure and diaphragmatic descent, transitioning from thoracic breathing during pregnancy to thoracoabdominal breathing. Blood pressure remains stable and within the normal range during the puerperium.
Uterine Involution
In the early postpartum period, the uterus feels firm and round, with the uterine fundus located one finger breadth below the umbilicus. On the first postpartum day, the uterine fundus rises to the level of the umbilicus and then descends by 1–2 cm daily. By the end of the first postpartum week, the uterus is palpable above the pubic symphysis. Around the 10th day postpartum, the uterus descends into the pelvic cavity, and the uterine fundus can no longer be felt on abdominal examination.
Afterpains
Intermittent, cramp-like pain in the lower abdomen caused by uterine contractions during the early puerperium is referred to as afterpains. This is more common in multiparous women. The pain intensifies during breastfeeding due to reflexive oxytocin release. Specific treatment is typically unnecessary.
Lochia
Lochia refers to the vaginal discharge postpartum, consisting of blood, secretions, necrotic decidua, and other materials shedding from the uterine lining. It has a bloody smell but no foul odor and typically lasts 4–6 weeks, with a total volume of 250–500 mL. Based on color, content, and duration, lochia is classified as follows:
- Lochia Rubra: Bright red due to a high blood content; it is heavy and may contain small clots. Microscopically, it contains abundant red blood cells, necrotic decidua, and some fetal membranes. Lochia rubra lasts 3–4 days, transitioning as bleeding decreases and serous fluid increases, forming lochia serosa.
- Lochia Serosa: Pale red-pink discharge due to its high serous content. Microscopically, it contains necrotic decidua, exudates, cervical mucus, few red blood cells and white blood cells, and some bacteria. It typically lasts about 10 days, with decreasing serous fluid and increasing white blood cells, transitioning to lochia alba.
- Lochia Alba: Milky and thick discharge due to large amounts of white blood cells. Microscopically, it contains white blood cells, necrotic decidua, epithelial cells, and some bacteria. Lochia alba lasts about three weeks. If uterine involution is incomplete, or if parts of the placenta, membranes, or infection remain, the amount of lochia may increase, and lochia rubra may persist with a foul odor.
Postpartum Sweating
Skin excretory function increases during the first postpartum week, resulting in profuse sweating, particularly during sleep and upon waking. This is considered normal but requires attention to fluid replenishment to prevent dehydration and heatstroke.
Management and Care During the Puerperium
During the puerperium, various physiological changes occur across maternal systems. While these changes are generally within the normal range, inadequate management or care can lead to pathological conditions.
Management During the Puerperium
Management in the First Two Postpartum Hours
The first two hours postpartum represent a critical period prone to severe complications such as postpartum hemorrhage, eclampsia, and postpartum heart failure. Close monitoring of maternal vital signs, uterine contractions, vaginal bleeding, uterine fundal height, and bladder fullness is essential. Vaginal bleeding should be measured quantitatively, especially in women at high risk for postpartum hemorrhage. In cases of uterine atony, uterine massage combined with the administration of uterotonic agents may be employed. If vaginal bleeding is minimal but uterine contraction remains weak with fundal elevation, intrauterine blood accumulation may be suspected, and uterine compression may be used to expel the retained blood while administering uterotonic agents. If the mother reports perineal or rectal pressure, posterior vaginal wall hematoma may be suspected, requiring vaginal or rectal examination for confirmation and timely intervention. Assistance with the first breastfeeding session should also be provided during this period. If no abnormalities occur during the first two hours postpartum, the mother and infant may be transferred back to the ward.
Diet
Light and easily digestible foods may be provided within the first two post-delivery hours, followed by a normal balanced diet. Foods should be nutrient-rich, calorific, and hydrating, with appropriate supplementation of vitamins and iron. Iron supplementation is recommended for three months postpartum.
Urination and Defecation
Spontaneous urination is encouraged as early as possible postpartum. Urination should be facilitated within the first four hours after delivery. In cases of difficulty, methods such as washing the urethral area with warm water, applying warm compresses to the lower abdomen, or gently stimulating the bladder through massage can help. Alternatively, intramuscular neostigmine may be administered to stimulate bladder contraction, with prior assessment of its contraindications. If these methods fail, an indwelling catheter may be necessary. Constipation may occur due to reduced physical activity, decreased dietary fiber intake, reduced intestinal motility, and diminished abdominal and pelvic floor muscle tone in the early puerperium. Vegetables should be consumed in adequate amounts, and early ambulation is recommended. In cases of constipation, oral laxatives may be administered.
Monitoring Uterine Involution and Lochia
Daily manual assessment of the uterine fundus height can help evaluate uterine involution. Measurements should be taken after the mother has emptied her bladder. The amount, color, and odor of lochia should also be observed daily. If there is incomplete uterine involution, characterized by increased and prolonged lochia rubra, uterotonic agents may be used as necessary. If infection is suspected, as indicated by foul-smelling lochia and uterine tenderness, broad-spectrum antibiotics may be administered to control the infection.
Perineal Care
The perineal area should be kept clean and dry. For those with perineal sutures, daily inspection should check for redness, swelling, induration, or discharge at the incision site. If wound infection occurs, interventions such as early suture removal, drainage, or debridement may be necessary.
Monitoring Emotional Changes
Maternal emotional instability may occur postpartum due to physical exhaustion from pregnancy and delivery, concerns about infant care, and discomfort during the puerperium. Mild depression is especially common between the third and tenth postpartum days. Reducing physical discomfort and providing emotional support, encouragement, and reassurance can help mothers regain confidence. Psychological assessments and postpartum depression screenings are recommended to enable early diagnosis and intervention.
Breast Care
Attention should be given to preventing breastfeeding-related complications such as engorgement, cracked nipples, or mastitis.
Prevention of Puerperal Heat Stroke
Puerperal heat stroke, a rare but acute febrile illness resulting from impaired thermoregulation due to excessive heat and humidity during the puerperium, can cause high fever, electrolyte imbalance, circulatory failure, and neurological damage. It typically arises in conditions of high temperature and humidity.
Stages of Heat Stroke:
- Early Heat Stroke: Symptoms such as thirst, sweating, palpitations, nausea, chest tightness, and fatigue may occur, with normal or mildly elevated body temperature.
- Mild Heat Stroke: Body temperature rises to above 38.5°C and is accompanied by flushed skin, chest tightness, rapid pulse and breathing, thirst, and heat rash.
- Severe Heat Stroke: Body temperature may reach 41–42°C with continuous high fever. Symptoms include pallor, rapid breathing, delirium, seizures, or coma. Untreated cases can lead to death within hours due to respiratory or circulatory failure. Survivors may experience irreversible central nervous system damage.
Prompt diagnosis and intervention, including changing the environment to lower temperature and improve ventilation, rapid cooling, and correcting water-electrolyte imbalances and acidosis, are essential. Recognition of symptoms is important for effective management.
Health Care During the Puerperium
The primary goal is to prevent complications such as postpartum hemorrhage and infection while promoting physiological recovery.
Diet and Rest
A well-balanced diet, adequate hydration, and proper rest are necessary. Cleanliness of the living environment and proper maternal hygiene should be maintained. Postpartum attire should be comfortable and breathable, and adequate ventilation in the living space is recommended.
Physical Activity and Postpartum Rehabilitation Exercises
Appropriate physical activity should begin as early as possible postpartum. Rehabilitation exercises promote recovery, improve urinary and bowel function, reduce the risk of thromboembolic diseases, and help restore pelvic floor and abdominal muscle tone. Exercise intensity should increase gradually.
Contraceptive Guidance
Contraceptive measures should be adopted in postpartum women resuming sexual activity. Barrier contraception is preferred for breastfeeding mothers, while non-lactating mothers may choose either barrier or hormonal methods.
Postpartum Checkups
Postpartum health assessments include home visits and follow-up examinations. Community healthcare providers generally conduct three visits postpartum: within the first week, at 14 days, and at 28 days. These visits evaluate the health status of the mother and infant, including:
- Assessment of maternal dietary habits and sleep patterns;
- Examination of the breasts and evaluation of breastfeeding;
- Monitoring uterine involution and lochia;
- Observation of perineal or cesarean incisions;
- Evaluation of maternal psychological well-being.
Abnormalities identified during these visits are addressed promptly.
A routine postpartum checkup at six weeks postpartum includes a general physical examination, such as blood pressure and heart rate assessment, as well as blood and urine tests to evaluate lactation status. Women with coexisting medical or obstetric complications may require additional testing. A gynecological examination assesses pelvic organ recovery, determining whether the reproductive organs have returned to their pre-pregnancy state. Concurrent infant checkups are also completed during this time.