ANATOMICAL AND PHYSIOLOGICAL CHANGES DURING PREGNANCY

PHYSIOLOGICAL CHANGES IN PREGNANCY Reproductive organs I. Uterus: The muscular organ holding the fetus during pregnancy, nourishment of the fetus through the placenta. It is divided into the body (Corpus, and fundus)and the cervix. During pregnancy, the uterus increases in weight from 60 to 1000g. In size, it changes from 6.5 to 32 cm. In a non pregnant state, the uterus is situated in the pelvic cavity. During pregnancy, it expands into the abdominal cavity. In addition to the growing foetus, uterine expansion is caused by an increase in connective tissue and in the size and number of blood vessels supplying the uterus

Uterine change during pregnancy

: b) Ligamentous supports: 1) Round ligaments are fibrous cords attaching to the uterus and libia majora During pregnancy, they become elongated and hypertrophied. They supportthe uterus in its move from the pelvic cavity into the abdominal cavity. 2) Broad ligaments are large folds of peritoneum separating the pelvis into the anterior and posterior divisions. The lower portion of the ligament is known asthe cardinal ligaments, it attaches the lateral aspect of the uterus to the supravaginal area of the cervix. 3) Utero sacral ligaments attach the sacrum to the posterior aspect of the cervix to support the cervix.

c) Cervix: The portion of the uterus connecting the body of the uterus and the vagina. 1) The internal os joins the body of the uterus with the cervix. 2) The external os opens into the vagina. 3) During pregnancy, the cervix is closed. A mucus plug forms over the cervix,providing a protective barrier between the vagina and the uterine contents.

4) During labour and delivery, the cervix shortens (or effaces) and widens (or dilates), effectively disappearing. A 10 cm opening is left between the uterus and the vagina to allow for passage of the foetus into the birth canal. 5) If the cervix begins dilating prematurely, it is sometimes stitched together during the second trimester, until the foetus in mature. This procedure is known as a cerclage.

II. Ovaries : The organs storing ova. Through hormonal influence, one ovum is developed per month. It then travels into the fallopian tube and has the potential to be fertilized. One ovary is located on either side of the uterus, encased in the posterior aspect of the broad ligaments.

III. Fallopian tubes: The ducts bringing mature ova from the ovaries to the uterus via peristaltic action. a) The fallopian tubes connect the uterine cavity to the abdominal cavity, near to the ovary. The opening at the abdominal site is lined with cilia to promote the peristalsis necessary to convey the ovum into the tube. b) They are situated in the superior margin of the broad ligaments

IV. Vagina: The connecting passage between the uterus and the perineum, serving as the birth canal a) The anterior borders include the bladder and the urethra. b) Laterally, the ureters and broad and round ligaments lie. c) Posteriorly, the peritoneum and the rectovaginal fascia.

R ESPIRATORY SYSTEM During pregnancy, the body is in a state of hyperventilation due to high level of progesterone. a. Breathing becomes more costal than abdominal. Additionally, most women are mouth breathers during pregnancy. b. Anatomically. the diaphragm is progressively elevated. Possibly because of expansion and elevation of the rib cage. Uterine pressure during the first and second trimesters does not appear to be a factor in this phenomenon

M ETABOLIC AND ENDOCRINE CHANGES 1. Relaxin is a hormone secreted by the corpus luteum. the endocrine body located in the ovary at the site of the ruptured ovarian follicle. a. Relaxin softens connective tissue during pregnancy in preparation for labour and delivery. when the pelvis must open to allow for the birth of the foetus. Relaxin. However is not specific to the pelvis. Other joints can also be affected. b. Relaxin peaks in early and late pregnancy. Women with chronic joint instability may notice an increase in symptoms during these times.

c. Relaxin has also been speculated to increased in the non pregnant women after ovulation and throughout the menstrual period. This may cause softening of the joints and pain in affected women. 2. Other major hormones effecting a woman during pregnancy include estrogen, progesterone. human placental lactogen, and 3. Edema is present in the hands. feet. face and eyelids. This is due in part to sodium and water retention. Additionally. hormones circulating by the placenta. ovaries, and adrenal cortex cause increased capillary permeability, which contributes to the edema many pregnant women experience.

M USCULOSKELETAL S YSTEM Abdominal muscles are stretched to the point of their elastic limit by the end of pregnancy. Hormonal influence on the ligaments is profound producing systemic decrease in ligamentous tensile strength and an increase in mobility of structures supported by ligaments and may predispose the patient to joint injury especially in the weight-bearing joints of the back, pelvis and lower extremities. The pelvic floor muscles must withstand the weight of the uterus, the floor drops as much as 2.5 cm.

Postural changes: During pregnancy, postural changes occur to accommodate for abdominal growth. a. These changes include forward head, rounded shoulders, increased lumbar lordosis, hyperextended knees, and pronated feet. b. The center of gravity changes, resulting in changes in balance. c. Muscular changes are also typical. often noted alterations include shortened hip flexors, lower back musculature, and pectorals. Abdominal muscles, neck, and upper back muscle groups elongate. This may promote stretch weakness or adaptive shortening.

Postural changes in pregnancy

Bones and joints: There is tendency to decalcification of bones, sublaxation of joints due to softening of ligaments by relaxin hormone. It is more marked in sacroiliac joint and symphysis pubis, leading to waddling gait.

C UTANEOUS SYSTEM Cutaneous system Due to overstretching of the skin, the elastic fiber may rupture together with small blood vessels and so red streaks appear; known as striae gravida rum. They are usually more marked below the umbilicus, on the breasts and may appear on the buttocks and thighs. In some women they are not marked or even don't appear during pregnancy. After labour, the red striae become pale silvery white due to fibrosis and are known as (striae albicantes).

Linea nigra

Pigmentation: It is due to suprarenal changes, it usually begins to appear after the 4th month. The pigmentation may appear anywhere but the commonest sites are: 1. Linea nigra: which is a line of pigmentation between the umbilicus and the symphysis pubis. 2. Increased pigmentation of the nipple as primary areola and appearance of the secondary areola.

Stria gravidarum

3. Cloasma gravidarum or mask face of pregnancy which is butterfly pigmentation of the forehead, nose, upper lip and the adjoining parts of the checks. This pigmentation may persist but the cloasma gravidarum usually disappears. Falling of hairs and brittleness of nails may occur during pregnancy.

Butterfly pigmentation

M ATERNAL WEIGHT GAIN There are no reliable data available for weight gain in the first 12 weeks of pregnancy. But in normal pregnancy the average gain is 0.3 Kg/week up to 18 weeks, 0.45 Kg/week from weeks and a slight reduction with a rate of Kg/week until term. Failure to gain weight and sometimes slight weight loss may occur in the last 2 weeks. The average weight gain for primigravidae for the inhal pregnancy is 12.5 Kg. and is probably about 0.9 Kg. less for multigravidae. Acute excessive weight gain is commonly associated with abnormal fluid retention.

Weight gain is produced by: Fetus Kg Placenta Kg Amniotic fluid Kg Uterus and breasts Kg Blood and fluid Kg Kg total= Muscle and fat kg

N ERVOUS SYSTEM Functional changes may appear especially in neurotic women as : -sleepy, depressed -while others become irritable, excited and suffer from insomnia. -The nausea and vomiting may have a neurotic element. -Change of appetite such as refusal of some types of food. -Neuralgias