Maternal Physiology Changes in Pregnancy PDF

ASENA AYAR MADENLİ ,MD ISTINYE UNIVERSITY FACULTY OF MEDICINE 65 Maternal Physiology The anatomical, physiological and biochemical adaptations in pregnancy are profound. Physiological adaptations of normal pregnancy can be misinterpreted as pathological and al...

ASENA AYAR MADENLİ ,MD ISTINYE UNIVERSITY FACULTY OF MEDICINE 65 Maternal Physiology The anatomical, physiological and biochemical adaptations in pregnancy are profound. Physiological adaptations of normal pregnancy can be misinterpreted as pathological and also unmask or worsen preexisting disease. Maternal Physiology Reproductive tract : Uterus : Stretching and hypertrophy of muscle cells. The walls of the corpus become thicker during the first few months of pregnancy, then they begin to thin gradually. By term, myometrium :1 to 2 cm thick Uterine hypertrophy: estrogen and perhaps progesterone. Subsequently, the organ increases more rapidly in length than in width and assumes an ovoid shape. Reproductive tract : Uterus : Uterine ascent from the pelvis, it usually rotates to the right This dextrorotation likely is caused by the rectosigmoid on the left side of the pelvis. Braxton Hicks contractions: appear unpredictably and sporadically and are usually nonrhythmic. Their intensity varies between approximately 5 and 25 mm Hg. Maternal-placental blood flow progressively increases during gestation principally by means of vasodilation. Reproductive tract : Cervix : Softening and cyanosis result from increased vascularity and edema of the entire cervix, together with hypertrophy and hyperplasia of the glands. The cervical glands undergo marked proliferation and normal pregnancy-induced changes represent an extension, or eversion, of the proliferating columnar endocervical glands. Red and velvety and bleeds even with minor trauma, such as with Pap smear sampling. Cervical mucus is rich in immunoglobulins and cytokines and may act as an immunological barrier to protect the uterine contents against infection. Result of progesterone; when cervical mucus is spread and dried on a glass slide, it is characterized by poor crystallization, or beading. ( Ferning ) Basal cells near the squamocolumnar junction are likely to be prominent in size, shape, and staining qualities. These changes are considered to be estrogen induced. Cervical eversion of pregnancy as viewed through a colposcope.The eversion represents columnar epithelium on the portio of the cervix. (Photograph contributed by Dr. Claudia Werne) Reproductive tract : Ovaries: Ovulation ceases during pregnancy, the single corpus luteum found during the first 6 to 7 weeks of pregnancy—4 to 5 weeks postovulation—and thereafter contributes relatively little to progesterone production. An extrauterine decidual reaction on and beneath the surface of the ovaries is common The diameter of the ovarian vascular pedicle grayscale ultrasound image demonstrates measurements of a corpus luteum cyst within the ovary increases during pregnancy from 0.9 cm to approximately 2.6 cm at term.  Relaxine : protein hormone is secreted by the corpus luteum as well as the decidua and the placenta in a pattern similar to that of human chorionic gonadotropin (hCG). Remodeling of reproductive-tract connective tissue to accommodate parturition. Initiation of augmented renal hemodynamics, decreased serum osmolality, and increased uterine artery compliance associated with normal pregnancy. (Despite its name, serum relaxin levels do not contribute to increasing peripheral joint laxity during pregnancy.)  Theca-Lutein Cysts: benign ovarian lesions result from exaggerated physiological follicle stimulation—termed hyperreactio luteinalis. associated with markedly elevated serum levels of hCG. asymptomatic, hemorrhage into the cysts may cause abdominal pain Maternal virilization may be seen. Reproductive tract : Vagina and Perineum : During pregnancy, increased vascularity and hyperemia develop in the skin and muscles of the perineum and vulva, with softening of the underlying abundant connective tissue Increased vascularity prominently affects the vagina and results in the violet color characteristic of Chadwick sign. Mucosal thickness, loosening of the connective tissue, and smooth muscle cell hypertrophy Vaginal discharge: Thick, white. The pH is acidic, varying from 3.5 to 6. This results from increased production of lactic acid from glycogen in the vaginal epithelium by the action of Lactobacillus acidophilus.  Increased vascularity prominently affects the vagina and results in the violet color characteristic of Chadwick sign. Reproductive tract : Breasts : Breast tenderness and paresthesias. Increase in size, and delicate veins become visible just beneath the skin. The nipples become considerably larger, more deeply pigmented, and more erectile. After the first few months, a thick, yellowish fluid—colostrum—can often be expressed from the nipples by gentle massage. During the same months, the areolae become broader and more deeply pigmented. Scattered through the areolae are a number of small elevations, the glands of Montgomery, which are hypertrophic sebaceous glands. Skin Changes : Abdominal Wall: Striae gravidarum or stretch marks : reddish, slightly depressed streaks commonly develop in the abdominal skin and sometimes in the skin over the breasts and thighs. Diastasis recti: Rectus muscles separate in the midline. If severe form a ventral hernia. Hyperpigmentation: elevated melanocyte-stimulating hormone and estrogen and progesterone also are reported to have melanocyte-stimulating effects. Chloasma or melasma gravidarum: mask of pregnancy: irregular brownish patches of varying size appear on the face and neck. The midline of the anterior abdominal wall skin— linea alba—takes on dark brown-black pigmentation to form the linea nigra. Pigmentation of the areolae and genital skin may also be accentuated.  These pigmentary changes usually disappear, or at least regress considerably, after delivery. Skin Changes : Stria gravidarum diastasis recti and chloasma Skin Changes : Vascular Changes: Consequence of hyperestrogenemia. Angiomas, called vascular spiders, particularly common on the face, neck, upper chest, and arms. Red skin elevations, with radicles branching out from a central lesion. Palmar erythema is encountered during pregnancy. Metabolic changes : Weight Gain Based on Pregnancy-Related Components Weight Gain: the average weight gain during pregnancy is approximately 12.5 kg Water Metabolism: Increased water retention during the pregnancy.  Electrolyte metabolism : Carbohydrate Metabolism: The GFR of Na and K is increased but, because of Mild fasting hypoglicemia enhanced tubuler resorption the excretion of these electrolytes are unchanged. Postprandial hyperglicemia Also,because of expanded volume, serum Hyperinsulinemia concentrations are decreased slightly. Suppression of glucagon Serum Ca levels decline. This reduction follows lowered plasma albumin concentrations. A Insulin resistance : estr /progesteron /hpl consequent decrease in the circulating protein- bound increase :act like GH-like action: increase nonionized calcium. Serum ionized calcium levels lipolysis and liberation of free fatty acids. remain unchanged. Serum Mg levels decline. Iodine requirements increase.  Fat metabolism Maternal hyperlipidemia Lipids lipoproteins and apolipoproteins increase. Increased insulin resistance and estrogen stimulation are responsible. Leptin increases.: regulation of increased maternal energy demands. Help to regulate fetal growth. Abnormally elevated leptin levels are associated with preeclampsia and GDM. Lipid metabolism in pregnancy and its consequences in the fetus and newborn Hematologic changes : Blood volume : %40-45 increases. Pregnancy induced hypervolemia: 1- it meets metabolic demands of the enlarged uterus and its greatly hypertrophied vascular system. 2-it provides abundant nutrients and elements to support the rapidly growing placenta and fetus. Results plasma and erythrocytes increase. More plasma than erythrocytes is added to the maternal circulation.Erythrocyte volume increase : 450 ml Moderate erythroid hyperplasia is present in bone marrow and reticulocyte count increases( relate to an elevated maternal plasma erythropoietin level ) Hematologic changes : Great plasma augmentation Hb and Htc concentration decrease and blood viscosity decreases. Av. term hb : 12,5 g /dl In the late pregnancy hb < 11 g /dl abnormal and due to iron deficiency rather than pregnancy hypervolemia. Iron : 1000 mg of iron required for normal pregnancy. 300 mg are actively transferred to the fetus and placenta. 200 mg are lost various normal excretion, gis. 450 ml : total circ. erythrocyte volume requires : 500 mg iron. 1 mL erythrocytes : 1,1 mg of iron. Hematologic changes : Early pregnancy : proinflammatory Mid pregnancy : antiinflammatory. T helper 1 IL-2 / INF Supression of /T gamma / secretions decrease. cytotoxic 1 TNF beta cells Parturition : influx of immune cells into myometrium to promote recrudescence of an inflammatory process. Upregulation Thelper 2 secretions increase. IL-4 IL6 IL13 cells Hematologic changes : PNL ( polymorphonuclear leukocyte) chemotaxis and adherence functions are depressed. ( Relaxin impairs neutrophil activation) Leukocyte count elevates,may approach 15000 / mml. During labor : attaining levels of 25000 / mml. CRP , ESR, procalcitonin increase Hematologic changes : Increased concentrations of clotting factors (except FXI) Clotting time doesnt differ significantly in normal pregnant women. Plasma fibrinogen increases Fibrinolytic activity is actually reduced. Increased plasminogen and decreased plasmin inhibitor , alfa2 antiplasmin. Platelets: decrased : due to hemodilutional effects. Thromboxan A2 production which induces platelet aggregation , progressively increases. Activated protein c resistance increases protein S and c decreases, factor VIII increases. Spleen, by the end of normal pregnancy, enlarges by up to 50 % compared with that in the first trimester. Hematologic changes : CARDIOVASCULAR SYSTEM Cardiac output is increased as early as the fifth week and reflects a reduced systemic vascular resistance and an increased heart rate. Brachial systolic blood pressure, diastolic blood pressure, and central systolic blood pressure are all significantly lower 6 to 7 weeks after the last menstrual period. The resting pulse rate increases approximately 10 beats/min during pregnancy. Between weeks 10 and 20, plasma volume expansion begins, and preload is increased. Ventricular performance during pregnancy is influenced by both the decrease in systemic vascular resistance and changes in pulsatile arterial flow. CARDIOVASCULAR SYSTEM: Heart: The heart is displaced to the left and upward and is rotated on its long axis. There is no change in septal thickness or in ejection fraction. Cardiac output increases 30 % Change in cardiac radiographic outline that occurs in pregnancy. Systemic vascular resistance decrease (%25). The blue lines represent the relations between the heart and thorax in the nonpregnant woman, and the black lines represent the BP decrases slightly. conditions existing in pregnancy (Redrawn from Klafen, 1927). Pulse rate increase 10-15 beat,  Supine Hypotension: During late pregnancy in a supine woman, the large uterus rather consistently compresses venous return from the lower body. It also may compress the aorta. In response, cardiac filling may be reduced and cardiac output diminished.  The diaphragm rises about 4 cm during pregnancy. RESPIRATORY SYSTEM: Functional residual capacity (FRC) decreases by approximately 20 to 30% or 400 to 700 mL during pregnancy. Expiratory reserve volume decreases 15 to 20 % or 200 to 300 mL. Residual volume decreases 20 to 125 % or 200 to 400 mL. Inspiratory capacity, the maximum volume that can be inhaled from FRC, increases by 5 to 10 % or 200 to 250 mL during pregnancy. Total lung capacity—the combination of FRC and inspiratory capacity—is unchanged or decreases by less With pregnancy, the subcostal angle increases, as does the anteroposterior and than 5 % at term. transverse diameters of the chest wall and chest wall circumference. These changes compensate for the 4-cm elevation of the diaphragm so that total lung capacity is not significantly reduced  The respiratory rate is essentially Total oxygen-carrying capacity, unchanged, but tidal volume and increases appreciably during normal resting minute ventilation increase pregnancy, as does cardiac output. significantly as pregnancy advances. Oxygen consumption increases Lung compliance is unaffected by approximately 20 % during pregnancy, pregnancy. Airway conductance is and it is approximately 10 % higher in increased and total pulmonary multifetal gestations. During labor, resistance reduced, possibly as a oxygen consumption increases 40 to result of progesterone. 60 %. URINARY SYSTEM: Kidney size increases approximately 1.5 cm Both the glomerular filtration rate (GFR) and renal plasma flow increase early in pregnancy. The GFR increases as much as 25 % by the second week after conception and 50 % by the beginning of the second trimester. (hyperfiltration): 1-hypervolemia-induced hemodilution lowers the protein concentration and oncotic pressure of plasma entering the glomerular microcirculation. 2- renal plasma flow increases by approximately 80 % before the end of the first trimester. Elevated GFR persists until term, even though renal plasma flow decreases during late pregnancy. Renal Changes in Normal Pregnancy  Relaxin Relaxin : may be important for Endothelin mediating both increased GFR and Nitric oxide renal blood flow during pregnancy. increases Renal aff and eff Renal blood flow and Renal vasodilation arteriolar resistance GFR  Serum creatinine levels decrease during normal pregnancy from a mean of 0.7 to 0.5 mg/dL. Values of 0.9 mg/dL or greater suggest underlying renal disease and should prompt further evaluation. Creatinine clearance in pregnancy averages 30 percent higher than the 100 to 115 mL/min in nonpregnant women. Glucosuria Hematuria / is usually due to contamination Proteinuria/unexpected not more than 150mg/day  Uterus displaces ureters laterally and compresses them at the pelvic brim. Ureteral dilatation is impressive, found it to be greater on the right side in 86 % of women: The dextrorotated uterus compression Dilated right ovarian vein complex, lies obliquely over the right ureter and may contribute significantly to right ureteral dilatation. GASTROINTESTINAL TRACT Pregnancy gingivitis : the gums may become hyperemic and softened and may bleed when mildly traumatized, as with a toothbrush. Epulis gravidarum : highly vascular swelling of the gums, The stomach and intestines are displaced by the enlarging uterus. The appendix, for instance, is usually displaced upward and somewhat laterally as the uterus enlarges. At times, it may reach the right flank.  Pyrosis (heartburn): caused by The serum albumin concentration reflux of acidic secretions decreases during pregnancy. By Gastric emptying time: one danger late pregnancy, albumin of general anesthesia for delivery is concentrations may be near 3.0 regurgitation and aspiration. g/dL compared with approximately Hemorrhoids: constipation and 4.3 g/dL in nonpregnant women. elevated pressure in veins below Gallbladder contractility is reduced the level of the enlarged uterus. and leads to increased residual Liver size doesnt change. volume. ENDOCRINE SYSTEM: The pituitary gland enlarges by approximately 135 %. During the first trimester, growth hormone is secreted predominantly from the maternal pituitary gland. Approximately 17 weeks, the placenta is the principal source of growth hormone secretion. Maternal plasma prolactin levels increase markedly during normal pregnancy.  Increase production of thyroid hormones by 40 to 100 %. serum TSH and hCG levels: The α- subunits of the two glycoproteins are identical, whereas the β-subunits, although similar, differ in their amino acid sequence. As a result of this structural similarity, hCG has intrinsic thyrotropic activity, and thus, high serum hCG levels cause thyroid stimulation. MUSCULOSKELETAL SYSTEM: Progressive lordosis is a characteristic feature of normal pregnancy. The sacroiliac, sacrococcygeal, and pubic joints have increased mobility during pregnancy. Although some symphyseal separation A. Symphyseal diastasis. Marked widening of the pubic symphysis (arrows) after vaginal likely accompanies many deliveries, those delivery. B. Sacroiliac (SI) joint widening; left (arrow) greater than right (arrowhead). (Images contributed by Dr. Daniel Moore.) greater than 1 cm may cause significant pain.  Intraocular pressure decreases during CENTRAL NERVOUS SYSTEM pregnancy and is attributed in part to and THE EYE increased vitreous outflow. Pregnancy-related memory declines and is Corneal sensitivity is decreased, and the limited to the third trimester. greatest changes are late in gestation. This decline was not attributable to Krukenberg spindles: brownish-red opacities depression, anxiety, sleep deprivation, or on the posterior surface of the cornea. other physical changes associated with pregnancy. It was transient and quickly resolved following delivery. difficulty with going to sleep, frequent awakenings, fewer hours of night sleep, and reduced sleep efficiency.