Definition and Anatomical Changes during Puerpuerium

The puerperium is the period following childbirth during which the organs, particularly the pelvic organ, revert to their pre-pregnancy anatomical and physiological states. It is the time after labor when the regenerative organs return to their pre-pregnant state, nursing begins, and the physical, hormonal, and emotional experiences of parturition are recovered. "Involution" refers to the process by which the regenerative organs return to their pre-pregnant state. The major ligament returns to their previous pregnancy as well. The stretched vagina, pelvic floor, perineum, bladder, and bowel restore tone, but a degree of laxity lingers in certain cases.

Anatomical changes in associated structures

Puerperium is the period following placental birth until the maternal organs in general, and the reproductive organs in particular, have restored to normal, during which the following physiological changes occur.

1. Changes in endocrine activity.
2. Involution of uterus or change in a uterus.
3. Lochia formation.
4. Changes in other body organs.

Change in Endocrine Activity

Oxytocin: The posterior pituitary gland secretes oxytocin hormone. This hormone causes the uterine muscle and breast tissue to contract, allowing milk to be released from the lactiferous tubules.

The action of oxytocin causes the placenta to separate during the third stage of labor. This action then stopped operating on the uterine muscle fibers, causing them to contract, shrinking the placental location, and preventing hemorrhage. Breast sucking by the infant increases greater oxytocin secretion, uterine involution, and milk evacuation.

Prolactin: After the placenta is removed, the levels of human chorionic gonadotrophin hormone, human placental lactogen, estrogen, and progesterone in the blood rapidly decrease. This results in a slew of physiological changes.

The decrease in estrogen permits prolactin, which is released by the anterior pituitary gland, to act on the alveoli of the breast, stimulating the production of breast milk. Lactating mothers have high prolactin levels, and the return of follicle-stimulating hormone is repressed, inhibiting the maturation of primordial follicles in the ovary.

Involution of the Uterus

The process through which the generative (reproductive) organs return to their pre-pregnant state is known as involution. This is caused by two processes:

1. Ischemia of the Uterus: Lack of blood flow to the uterus owing to uterine muscle contraction and retraction, which compress the uterine blood vessels after the third stage of labor, causing the uterus to shrink.
    
2. Autolysis of Fibers: Extra muscle fibers dissolve on their own. Some are taken into the circulation and expelled by the kidney, while the remaining are discharged as lochia by the uterus. The uterus weighs around 1kg (900gm) after the end of labor. It has reverted to its pre-pregnancy weight of 60gm at the end of the puerperium.

Lochia Formation

The term lochia refers to the discharge from the uterus after childbirth and abortion. It has an alkaline response, which allows the organism to proliferate more quickly than regular acid secretion of the vagina. It comes in three varieties. As involution progresses, the lochia alters.

1. Lochia rubra/red lochia
   This is crimson in color and consists of placental blood and debris from the deciduas and chorion. It consists primarily of blood, leucocytes, deciduas, and mucus and is visible during the first three days of puerperium.
2. Lochia serosa/ pink lochia
   This is pink in color and discharges from the fourth to the seventh day. This lochia contains more serum, leucocytes, and bacteria, as well as less placental blood.
3. Lochia alba/white lochia
   The discharge becomes paler, milky brown, and finally white. It contains leucocytes, cervical mucus, serous exudates, granular epithelial cells, cholesterol crystals, and healing tissue debris, among other things. It normally lasts up to 10-15 days, however, it can sometimes last up to 3-4 weeks.

Changes in Other Body Organs

1. Cervix: The cervix is flabby, ill-defined, and deflated immediately after labor. The cervical aperture gradually closes and, for the first several days after birth, easily admits two fingers. Only one finger can be admitted by the end of the first week.
2. Vagina: Gradually returns to normal size Rugae reappear in the third week, although never to the same extent as before. Granulation tissue heals minor lacerations that are unavoidable.
3. The urinary tract: After delivery, the urinary system was alleviated of pressure. Because the kidneys secrete vigorously and the bladder regularly fills quickly, the mother must micturate frequently. During labor, the bladder is pushed into the belly, straining the uterus significantly and potentially causing urethral bruising and loss of bladder muscle tone.
4. The kidneys: Renal activity is elevated in the early stages of puerperium due to decreased blood volume and the excretion of autolysis waste products. The activity peaks within the first 7 days of puerperium.
5. Pelvic floor, perineum, vagina, vulva, and bowel: The decrease in circulating progesterone reserves its influence on the smooth muscle fibers of the pelvic floor, premium, vagina, and intestine.
6. The cardio-vascular system: Normal blood volume increases during pregnancy to meet the increased blood flow required by the placenta and uterine blood vessels.
7. Other changes: The decrease in estrogen and progesterone causes a number of other physiological changes. Normal blood volume is significantly raised during pregnancy.
8. Lactation: It develops during puerperium. The impact of estrogen and progesterone on both the glandular and tubular systems of a breast causes the breast to develop significantly during pregnancy.