Physiological Changes in the Reproductive System

Subject: Midwifery I (Theory)

Overview

The physiological changes that occur in the mother during pregnancy allow her to produce and maintain a healthy environment for adequate fetal growth without jeopardizing her own health. The alterations that occur during pregnancy are transitory adaptions. These changes prepare the mother to meet the fetus's requirements and demands, and the abdominal cavity holds a fetus. Vulva becomes edematous and hyperemic, and superficial varicosities may occur, especially in multiparae.

The physiological changes that occur in the mother during pregnancy allow her to produce and maintain a suitable environment for fetal growth while not jeopardizing her own health. Pregnancy changes are a transitory adaption. These modifications prepare the mother to satisfy the fetus's requirements and demands, and the abdominal cavity contains a fetus. It is indicated which systems of the mother's body undergo alterations. This change is primarily the result of changes in:

  1. Hormonal production
  2. Circulation
  3. Metabolism

Vulva:

Vulva becomes edematous and hyperemic, and superficial varicosities develop, particularly in multiparae. Libiaminora is hypertrophied and pigmented.

Vagina:

Pregnancy induces an increase in blood supply to the vagina, which results in the following alterations.

  1. Softening of vaginal tissues, allowing for easier distension during labor.
  2. Jacquemier's sign is a purple discoloration of the vagina.
  3. Osiander's sign refers to uterine artery pulsation felt through the lateral fornices.
  4. When the pH of the vaginal discharge becomes acidic (3.5 – 6), it turns white.

Changes in the Cervix:

During pregnancy, the cervix becomes vascular, edematous, and soft, its length doubles, and its volume increases. The cervix has more fibrous tissue and less muscle tissue than the uterine body. The width of the cervix has increased marginally. It will be purple and velvety upon examination.

Endocervical cells create mucus under the influence of progesterone, which thickens and becomes more viscous during pregnancy. The operculum is a thicker mucus from the cervical plug that guards against ascending infection.

In late pregnancy, the cervix softens in response to increased painless contractions, prostaglandin release from local tissue, and decreased collagen concentration within the cervix, making it more distensible in preparation for labor.

The Body of the Uterus:

Following conception, the uterus grows to provide a nutritional and protective environment for the developing and growing fetus.

  1. Decidua: During pregnancy, the endometrium is referred to as the decidua; progesterone and estrogen produced by the corpus luteum induce the decidua to thicken, become richer, and become more vascular at the fundus and in the upper body of the uterus. These are the most common locations for implantation. In the lower pole of the uterus, the decidua is thinner and less vascular. Until the trophoblast cells begin to build the placenta, the blastocyst lives in a glycogen-rich environment provided by the decidua. When the placenta develops, it is capable of producing its own hormone.
     
  2. Myometrium: Estrogen is in charge of uterine muscle growth. Hypertrophy refers to a rise in the size of muscle fibers, whereas hyperplasia refers to an increase in their number. For the first 20 weeks, the uterus grows in this manner. Following that, it stretches to accommodate its contents, increasing in weight from 60 to 900 grams and in size from 7.5cm * 5cm *2.5cm to 30cm *22cm *20cm. Because progesterone causes smooth muscle relaxation, the uterus can stretch in this manner. However, even at 16 weeks of pregnancy, the uterus begins to produce mild waves of contraction known as Braxton hicks contractions. Contraction is normally painless, however, some women do experience discomfort. Braxton hicks contractions continue for around 60 seconds.
     
  3. Muscle layer: The cornu, lower uterine segment, and cervix are all surrounded by the inner circular layer. During labor, this circular Layer is engaged in the stretching of the lower segment and the cervix.
    The contraction required to remove the fetus at the conclusion of pregnancy is caused by the middle oblique layer. This movement is also required after the placenta is delivered to entrap and enmesh blood arteries and ligate them.
    During labor, the outer longitudinal layer, and muscle fibers touch and retract, causing the top segment to thicken. The thick upper section functions as a piston, forcing the fetus into the passive lower part in order to eject the infant.
  4. Perimetrium: It is a peritoneum layer. It does not completely encircle the uterus. It allows for unrestrained uterine growth.

  • Uterine Growth:
    The uterus expands into the pelvic cavity throughout the first 12 weeks of pregnancy. It rises into the abdominal cavity at about 12 weeks, and the fundus can be palpated immediately above the symphysis pubis. The uterus loses its natural posture and grows erect; however, following the 20th week of pregnancy, it returns to its original position.
    The uterus is about midway between the symphysis pubis and the umbilicus by the 16th week. It is around 1" (finger) below the umbilicus at 20 weeks. It is 1 finger above the umbilicus at 24 weeks. When the expanding uterus comes into contact with the mother's abdominal walls between 16 and 20 weeks, the mother may feel fetal movement; this sensation is known as "quickening," which indicates "life." At 30 weeks, the fundus is located halfway between the umbilical cord and the xiphisternum. At 36 weeks, the fundus elevates the xiphisternum and may get involved in the pelvis, lowering the pelvic level to that of 34 weeks of pregnancy.

  • Changes in Uterine Shape:
    Adequate nutrition was essential for the fetus's healthy growth. The embedded blastocyst requires minimal space after conception, but the upper region of the uterus begins to grow due to an estrogen action. To accommodate the increasing amount of fluid and placental tissue, the uterus changes from a pear shape to a globular shape in early pregnancy from a pear shape during the 12th week of pregnancy. This puts strain on the other pelvic organ.
    The isthmus softens and elongates from its original size until 10 weeks of pregnancy, when it measures 25mm, giving the impression of a stalk beneath the globular upper segment.

References

  • Kovacs CS. Calcium metabolism during pregnancy and lactation. NCBI Bookshelf. http://www.ncbi.nlm.nih.gov/books/NBK279173/
  • HealthLine. 2005. 2017 http://www.healthline.com/health/pregnancy/bodily-changes-during
  • BC Open Textbook. https://opentextbc.ca/anatomyandphysiology/chapter/28-4-maternal-changes-during-pregnancy-labor-and-birth/
  • Hadassah Medical Center. http://www.hadassah-med.com/giving-birth/hadassah-birthing-club/throughout-pregnancy/physiological-changes-during-pregnancy
  • Tuitui R. 2002, A textbook of Midwifery A (Antenatal), 3rd edition, Vidyarthi Pustak Bhandari (Publisher and Distributor), Bhotahity, Kathmandu
  • Tuitui R. 2002, A textbook of Midwifery B (Intranatal), 3rd edition, Vidyarthi Pustak Bhandari (Publisher and Distributor), Bhotahity, Kathmandu
Things to remember
  • The physiological changes that occur in the mother during pregnancy allow her to produce and maintain a suitable environment for fetal growth while not jeopardizing her own health.
  • Pregnancy changes are a transitory adaption. These modifications prepare the mother to satisfy the fetus's requirements and demands, and the abdominal cavity contains a fetus.
  • Physiological changes in the reproductive system include the edematous and hyperemic vulva, as well as the appearance of superficial varicosities, particularly in multiparae.
  • Libiaminora is hypertrophied and pigmented.
  • During pregnancy, there is an increase in blood supply to the vagina, which causes changes such as softening of the vaginal tissues, which allows for easier distension in labor, and purple staining of the vagina, known as Jacquemier's sign.
  • During pregnancy, the cervix becomes vascular, edematous, and soft, its length doubles, and its volume increases.
  • The cervix has more fibrous tissue and less muscle tissue than the uterine body.
  • Following conception, the uterus grows to provide a nutritional and protective environment for the developing and growing fetus.
  • The embedded blastocyst requires minimal space after conception, but the upper region of the uterus begins to grow due to an estrogen action.
  • To accommodate the increasing amount of fluid and placental tissue, the uterus changes from a pear shape to a globular shape in early pregnancy from a pear shape during the 12th week of pregnancy.
Videos for Physiological Changes in the Reproductive System
Maternal changes in pregnancy
Questions and Answers

Physiological Changes in the Reproductive System

Vulva

The vulva becomes edematous and hyperemic, and superficial varicosities may form, especially in multiparae. Libiaminora is pigmented and has hypertrophy.

Vagina

The changes listed below are brought on by pregnancy's markedly increased blood flow to the vagina.

  • Vaginal tissues soften, facilitating easier labor distension.
  • The genitalia have a purple discoloration known as the Jacquemier's sign.
  • The uterine artery pulsation that is felt through the lateral fornices is known as the Osiander's sign.
  • More vaginal discharge, which is often white when the pH is acidic (3.5 – 6).

Changes in Cervix

  • During pregnancy, the cervix doubles in length, develops vascularity, edema, and softness, and increases in volume. The cervix has less muscular tissue and more fibrous tissue than the body of the uterus. The width of the cervix has slightly increased. Upon inspection, it will appear crimson and supple.
  • Under the influence of progesterone, endocervical cells secrete mucous, which during pregnancy thickens and becomes viscous. The thickened mucus, or operculum, of the cervical plug serves as defense against ascending infection.
  • The cervix softens as labor progresses as a result of an increase in painless contractions, local tissue prostaglandin release, a drop in the level of collagen within the cervix, and an increase in distensibility.

The Body of Uterus

After conception, the uterus expands to provide the developing fetus with a nurturing and safe environment.

  • Decidua
    • During pregnancy, the endometrium is referred to as the decidua. Progesterone and estrogen, which are originally produced by the corpus luteum, cause the decidua to thicken, become more vascularized, and become richer at the fundus and in the upper body of the uterus. These are where implants are typically placed. In the lower pole of the uterus, the decidua is thinner and less vascular. Up until the trophoblast cells start to form the placenta, the blastocyst is housed in the glycogen-rich decidua. The placenta can create its own hormone when it is developing.
  • Myometrium
    • Growing uterine muscle is a result of estrogen. Hypertrophy refers to a rise in the size of the muscle fibers, and hyperplasia refers to an increase in their number. For the first 20 weeks, this is how the uterus grows. After that, it stretches to make room for its contents, which weigh an additional 60 to 900 g and grow in size from 7.5 cm to 5 cm to 20 cm. Progesterone induces smooth muscle relaxation, which allows the uterus to stretch in this fashion. However, the uterus starts to produce Braxton hicks contractions as early as 16 weeks of gestation. Although most women don't feel pain during contractions, some do. Throughout the course of pregnancy, braxton hicks contractions, which last for about 60 seconds, continue. Later, they transform into labor contractions.
  • Muscle layer
    • The cervix, lower uterine segment, and cornu are encircled by the inner circular layer. During labor, this circular layer helped to extend the cervix and lower segment.
    • The contraction required to remove the fetus at the conclusion of pregnancy takes place in the middle oblique layer. Additionally, after the placenta is delivered, it is necessary to perform this action to entrap, enmesh, and ligate bleeding vessels.
    • During labor, the outer longitudinal layer of muscle fibers contacts and retracts, causing the upper segment to become excessively thick. The fetus is forced into the appropriate passive lower segment by the thick upper segment, which acts as a piston to expel the child.
  • Perimetrium
    • It is a peritoneal layer. The uterus is not entirely covered. It permits the uterus's unrestricted growth.

Uterine Growth

The uterus grows into the pelvic cavity throughout the first 12 weeks of pregnancy. When it enters the abdominal cavity at 12 weeks, the fundus is palpable immediately above the symphysis pubis. The uterus loses its normal position and becomes erect; however, after the 20th week of pregnancy, it returns to its normal position, albeit slightly to the right.

The uterus is about halfway between the symphysis pubis and the umbilicus by the sixteenth week. It is a finger's width below the umbilicus at 20 weeks. It is one finger above the umbilicus at 24 weeks. The mother may occasionally feel fetal movement between 16 and 20 weeks when the expanding uterus makes touch with the mother's abdominal walls; this movement is referred to as "quickening," which means "life." The fundus is situated halfway between the xiphisternum and the umbilical at 30 weeks. At 36 weeks, the fundus raises the xiphisternal level and has a chance to engage in the pelvis, where the level of the pelvis is roughly equivalent to that of 34 weeks of pregnancy.

Changes in Uterine Shape

Adequate was necessary for the fetus's healthy growth. After fertilization, the attached blastocyst occupies little space, but estrogen's action causes the top section of the uterus to grow. To accommodate growing amounts of liquor and placental tissue, the uterus transforms from its pear-shaped state in the 12th week of pregnancy to a globular state in the early stages of pregnancy. The other pelvic organ is put under pressure by this.

At 10 weeks of pregnancy, the isthmus, which makes up the lower portion of the uterus, measures 25 mm, giving the upper segment, which is globular in shape, the appearance of a stalk.

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