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Physiologic Adaptations to Pregnancy

Physiologic Adaptations to Pregnancy. Reproductive System. 1.Uterus: A.Growth : Uterus changed in size shape and position during pregnancy Before pregnancy the uterus is small, pear shaped and pelvic organ. Weight 50-70gm , and has a capacity 10ml.

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Physiologic Adaptations to Pregnancy

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  1. Physiologic Adaptations to Pregnancy

  2. Reproductive System 1.Uterus: A.Growth:Uterus changed in size shape and position during pregnancy • Before pregnancy the uterus is small, pear shaped and pelvic organ. Weight 50-70gm, and has a capacity 10ml. • At the end of pregnancy, the uterus weighs 800-1200gm and has a capacity of 5000ml.

  3. Uterine growth (enlargement): 1.During the first trimester the enlargement due to: Hyperplasia caused by stimulation of myometrium by estrogen 2.During the second and third trimesters: uterine growth are mainly related to hyperplastic and hypertrophic growth of muscle fibers to accommodate the growing fetus

  4. Uterine Growth During Pregnancy Fig. 13-1

  5. B.Uterine Contractility • Throughout pregnancy the uterus undergoes irregular, painless contractions called Braxton Hicks contraction. • During the third trimester these contraction occur more frequently and may be mistaken by true contractions, they are called false labor.

  6. C.Uterine blood flow: As the uterus increases in size, blood flow increases dramatically, during late pregnancy, blood flow to the uterus and placenta reaches 450 to 650 ml/min.

  7. 2.Cervix • A. Chadwick’s sign:bluish purple color that include vagina and labia, this discoloration is one of the earlier signs of pregnancy. • B. Goodell’s sign: (cervical softening ), Collagen fibers in the connective tissue of cervix decrease, causing the cervix to soften. C.Mucus plug:Thecervical glands proliferate and the mucus fills the endocervical canal, this mucus form a plug that blocks the ascent of bacteria from vagina to uterus.

  8. 3.Vagina and vulva • Bluish color of vaginal wall result from increased vascularity. • Softening of connective tissue and thickening of vaginal mucosa to allow distension during labor. • Vaginal cells contain increasing amounts of glycogen, which causes rapid sloughing and increased vaginal discharge.

  9. Increased vascularity, edema of vulva and varicosities from pelvic congestion and heavy uterus. • PH of vaginal secretion (discharge) is acidic which prevent growth of harmful bacteria found in vagina, but yeast infections are common during pregnancy.

  10. 4.Ovaries Cessation of ovulation because of increase level of Estrogen And Progesterone which inhibit FSH andLH

  11. 5.Breast • Change in size and appearance because of the effect of Estrogen and Progesterone. • Breast become highly vascular with a visible network of veins. • Stria: (stretch marks) may appear on the breast because of the extensive increase in breast size.

  12. Increase nipple size and become more erected. • Areola become (larger and more pigmented, secondary areola may develop). • Tubercles of Montgomery (sebaceous glands) become more prominent during pregnancy and secrete a substance that lubricates the nipples.

  13. Colostrum: thick, yellowish breast fluid presents in varying a mounts from 12-16 weeks of pregnancy, can be expressed by third trimester.

  14. Cardiovascular system 1. Heart size and position • Cardiac hypertrophy:increase workload lead to slight muscle enlargement • Heart shift upward and toward left as the uterus push diaphragm. • 2.Heart sounds: During pregnancy (12-20 weeks to 2-4 weeks after birth), some heart sounds may be altered to the extent that they would be considered abnormal in the non pregnant state. • Splitting of the first heart sound and systolic murmurare the most common changes in heart sound.

  15. 3.Blood volume: -.Total blood volume increasesby 30% t0 50% -Plasma volume increase progressively of 40% -60% (1200-1600ml) above nonpregnant values -Red blood cells increase 250-450 ml about 20%-30% above pre pregnancy value. Increase plasma volume more than RBCs result in dilution which lead to physiologic anemia or pseudoanemia of pregnancy

  16. -Iron Deficiency Anemiaoccurs when HB less than 11g/dl in first and third trimester and less than 10.5g/dl in second trimester.

  17. 4.Cardiac output: it rises up to 50% during the first half of pregnancy and remains elevated throughout pregnancy. The heart rates (HR) increase about 10 to 20 beat/ minute above baseline. Cardiac output is highest in lateral position and lowest in supine position 5.Peripheral Vascular Resistance: falls because of many factors during pregnancy

  18. 6.Blood pressure: systolic blood pressure remains unchanged or decreased. And diastolic may decrease by 10-15 mmHg by 24-32 weeks of gestation By end of third trimester BP returns to non pregnant level.

  19. Effect of position on blood pressure Supine hypotensionwhen the pregnant woman is in supine position, during second half of pregnancy. The weight of the uterus partially occludes (obstruct) the vena cava and the descending aorta which impedes return of blood from lower extremities and reduces cardiac return, cardiac output and blood pressure.

  20. Blood flow through the placenta also decreases if the woman remains in the supine position for a prolonged period and decreased blood flow could result in fetal hypoxia. • Turning to lateral position alleviates the pressure on the blood vessels and correct the hypotension.

  21. Vena Caval Syndrome (Supine Hypotensive Syndrome) Fig. 13-4a

  22. 7.Blood components: • Increased erythrocytes (RBCs) by 25%-33% which greatly increase the maternal demand for iron which is necessary for hemoglobin formation. • Increased leukocytes 5,000-12,000 during pregnancy as high as 15000. ,reach as high as 25,000 during labor and early postpartum. • Increase plasma fibrinogen (factor I)50% which increase ability to form clots (thrombophlebitis may develop).

  23. Respiratory system 1.Oxygen consumption: increases by about 20%. Half of the oxygen is used by the fetus and the placenta. To compensate the increased need for oxygen, the woman breathes more deeply, although her respiratory rate remains unchanged.

  24. 2. Hormonal factors: a.Progesterone 1.Heightened awareness of the need to breathexperienced by many women during pregnancy. Because of two factors 1.Progesterone and prostaglandins cause decreasing airway resistance by relaxing the smooth muscle in respiratory tract. 2.Progesterone raises the sensitivity of the respiratory centre to CO2

  25. b.Estrogen • Nasal stuffiness, epistaxis and voice change . • Sense of fullness in the ears because of edema of the ear drum and Eustachian tubes

  26. 3.Physical changes 1.The uterus lifts the diaphragm by about 4cm by the third trimester. 2.The volume of the lung is decreased 3.The anterioposterior diameter of the chest expand by 2 cm These changes caused by the relaxation of the ligaments around the ribs from the relaxinhormone. 4.Breath become thoracic rather than abdominal and many women experience dyspnea.

  27. Gastrointestinal system A.Mouth:1.Gingivitis and bleedingfrom hyperemia (is the increase of blood flow to different tissues in the body)2.Ptyalismor excessive salivation from unknown cause. B.Esophagus:Pyrosisbecause of the effect of the progesterone on the smooth muscles the lower esophageal sphincter tone decrease during pregnancy causes reflux of acidic stomach into the esophagus causes heartburn

  28. C. Stomach and small intestine1.Decreased gastrointestinal tone and motility caused by progesterone. 2.longer emptying time of stomach and small intestine to allows additional time for nutrients absorption especially calcium and iron 3. Nausea and vomiting during first trimester d. Large intestine: constipation andhemorrhoids because of decreased motility of large intestine to allow more time for water absorption

  29. E. Liver and gall bladder: 1.Prolonged emptying time of gall bladder resulting in thicker bile which predispose the development of gall bladder stone 2.Decreased gall bladder tone also cause retain bile salts which can lead to itching (Pruritus).

  30. 3.During the third trimester the liver is pushed upward and backward by the uterus which altered the liver functions. 4.Serum alkaline phosphatase rises two to four time than non pregnant woman 5.Serum albumin levels and total protein fall gradually

  31. Urinary system A. Bladder 1.Frequency and urgency of urination through out pregnancy 2.Nocturia ,urgency and stress incontinence 3.Bladder capacity doubles by term because of increased level of progesterone. 4.Bladder mucosa becomes congested with blood and hypertrophied because of the estrogen making it susceptible to trauma and infection during childbirth.

  32. b. Kidneys and uterus: • 1.Dilation of renal pelvis and ureters caused by progesterone leadtochange in kidney shape and size. 2.The flow of urine through the uretes is obstructed ,the ureters and renal pelvis dilate resulting in stasis of urine allows time for bacteria to multiply and increase risk of urinary tract infection.

  33. C.Functional changes 1.Renal blood flow increases by 50% to 80% by the end of the first trimester ,then decreases to term. This increase because of increase in plasma volume and cardiac output 2.Glomular filtration rate increase by 50% and also renal plasma flow rate These two functions are important to excrete additional metabolic waste from mother and fetus. 3.But they affect the excretion of glucose (Glycosuria). Glycosuria is another cause of UTI during pregnancy.

  34. 4.Mildproteinuria is common and consider normal 5.Plasma concentration of creatinine and urea normally decline because of increasedGFR

  35. Integumentary system Skin 1. Sweating, feeling of warm. related to increase circulation to the skin 2.Hyperpigmentation: starts as early as 2nd month because of the increased level of the melanocyte stimulating hormone (MSH) caused by estrogen and progesterone. a.Chloasma, melasma or mask of pregnancy (brownish patches over forehead, cheeks and bridge of nose) b.Linea nigra (extends from symphysis pubis to the top of fundus) c.Darkening of areola and nipples.

  36. 3.Cutaneous vascular changes: a.Vascular spider nevi tiny red elevations that branch in all directions appear on face, neck, upper chest and arms. b.Palmar erythema redness of palms and soles. 4.. Connective tissue: Stria gravidarum (stretch marks): linear tears occur in the connective tissue appear on abdomen, breasts and buttocks. 5. Hair :hair grows more rapidly and less hair falls during pregnancy

  37. Musculoskeletal system 1.Calcium storage: fetal demands of Ca increase especially in the 3rd trimester. Absorption of Ca also increase. There is no loss of maternal bone density to meet fetal needs. 2.Postural changes: increased mobility of pelvic ligaments and joints caused by relaxin and progesterone lead to pelvic instability andwaddling gait of pregnancyto compensate for changing centre of gravity which shift forward.

  38. Lordosis posture related to increase uterine size so the woman lean backward to maintain balance which may lead also to backache. 3. Abdominal wall: during the 3rd trimester the abdominal muscles may become stretch cause rectus abdominis muscles separate (diastasis recti) this separation might be slight or severe.

  39. Endocrine system 1.Pituitary glands: Anterior pituitary gland produce prolactine to prepare breasts to produce milk. Posterior pituitary glands secretes oxytocinto stimulate milk ejection. Its action on contraction is inhibited by progesterone during pregnancy. 2.Thyroid glands: slight enlargement of thyroid gland related to increase total Thyroxin (T4) causes increase in basal metabolic rate (BMR)

  40. 3.Parathyroid gland: Slight decrease of parathyroid hormone during 1st trimester and normal during rest of pregnancy. 4. Pancreas: Glucose level are 10%-20% lower than before pregnancy and hypoglycemia may develop at night and between meals During the second half of pregnancy maternal tissue sensitivity to insulindecline related to effect of placental hormones.

  41. The resulting higher blood glucose level makes more glucose available for the fetal energy needs and stimulates the pancreas of a healthy woman to produce insulin. Inadequate insulin production results in gestational diabetes.

  42. 5.Adrenal gland 1. Cortisol level is elevated which regulates carbohydrates and protein metabolism It stimulate the gluconeogenesis (the generation of glucose from non-carbohydrate carbon substrates )when glucose is inadequate to meet body needs 2. Increased aldosterone to overcome the salt wasting effects of progesterone to maintain the necessary level of sodium

  43. Changes in metabolism 1.Weight gain2.Water metabolism: water requirements increased during pregnancy. Increased glomular filtration rate (GFR) and progesterone result in increased sodium excretion, but on the other hand increased estrogen, cortisole and aldesterone promote reabsorption of sodium so sodium balance is maintained.

  44. 3.Dependant edema: in the later pregnancy result from delays venous return caused by enlarging weight of the uterus so veins of the legs become distended and shift of fluid from vascular compartment to interstial spaces. -Edema of the feet and ankles is obvious. If edema of face or hands is noted, further assessment for hypertension or proteinuria is essential. -About 6 to 8 liter of fluid is retained duringpregnancy

  45. 4. Carpal Tunnel Syndrome:compression of median nerve caused by edema may lead to carpal tunnel syndrome. Symptoms include (pain, burning, numbness, or tingling of the hand and wrist. Splinting the wrist during the night might be necessary.

  46. Sensory organs • Eye: • Thickening and corneal edema • Decreases intraocular pressure • Ear • Blocked ears and mild temporary hearing loss,because of changes in mucous membrane of Eustachian tube from estrogen

  47. Immune System • Immune function is altered during pregnancy to allow the fetus which is foreign tissue for the mother to grow undisrupted without being rejected by the mother

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