Maternal Physiology in Pregnancy

By La Lura White MD

Maternal Fetal Medicine

Maternal Physiology in Pregnancy Major adaptations in maternal anatomy,

physiology, and metabolism are required for successful pregnancy.

Nearly every organ system is affected.

Understanding these changes helps to distinguish the normal physiology of pregnancy from pathological disease states.

Maternal Physiology in PregnancyThese changes create a myriad of pregnancy symptoms that include

Nausea/Emesis (morning sickness)

Headaches Backaches Urinary frequency Hemorrhoids/Constipation

Leg Cramps Edema more common

lower extremity Breast tenderness Paresthesis Varicose veins

Maternal Physiology in Pregnancy Due to the pregnancy effect on major organ systems

including: Nutritional Digestive Tract Changes Urinary System Cardiovascular System Respiratory System Metabolism Skeletal Endocrine Integument Ocular

Maternal Physiology in Pregnancy: Nutritional

During pregnancy, nutritional requirements, including those for vitamins and minerals, are increased, and several maternal alterations occur to meet this demand.

Addition of 300 kcal/day.

The mother`s appetite usually increases, so that food intake is greater, although some women have a decreased appetite or experience nausea and vomiting.

These symptoms may be related relaxation of smooth muscle, increasing levels of human chorionic gonadotrophin (hCG) and estrogen.

Maternal Physiology in Pregnancy Complicates 70% of pregnancies normally from 4-16 weeks True Hyperemesis gravidarum (HG) is a severe form of

morning sickness, with "unrelenting, excessive pregnancy-related nausea and/or vomiting that prevents adequate intake of food and fluids, “that may requiring hospitalization, IV fluids, anti-emetics even protonics or TPN

Pica: craving for substances that are not food Etiology unknown Check for poor weight gain and refractory anemia South - clay or starch (laundry or cornstarch) UK – coal Also soap, toothpaste and ice

Maternal Physiology in Pregnancy: Digestive Tract Changes

If the pH of the oral cavity decreases, tooth decay may occur linked to pre-term deliveries.

Tooth decay during pregnancy, however, is not due to lack of calcium in the teeth, dental calcium is stable and not mobilized during pregnancy as is bone calcium.

The gums may become hypertrophic, hyperemic and friable; this maybe due to increased systemic estrogen.

Vitamin C deficiency also can cause tenderness and bleeding of the gums.

Maternal Physiology in Pregnancy: Digestive Tract Changes

Gingivitis of pregnancy: vascular swelling of the gums can lead to the development of pyogenic granulomas :

Epulis gravidarum:

regress 1-2 mos after delivery

excise if persistent or excessive bleeding

Maternal Physiology in Pregnancy: Digestive Tract Changes Gastrointestinal Motility

Reduced during pregnancy due to increased levels of progesterone, which decrease the production of motilin, a hormonal peptide that is known to stimulate smooth muscle in the gut.

Transit time of food throughout the gastrointestinal tract much slower, more water than normal is reabsorbed, leading to constipation.

Maternal Physiology in Pregnancy: Digestive Tract Changes

Decreased tone and motility secondary to progesterone Esophagus :dysmotility Esophageal peristalses is deceased, accompanied by gastric

reflux because of the slower emptying time and dilatation or relaxation of the cardiac sphincter.

Stomach Reduced tone of the gastroesophageal junction sphincter Production of the hormone gastin increases significantly,

resulting in increased stomach volume and decreased stomach pH.

Maternal Physiology in Pregnancy

Gastric compression due to enlarging uterus with decrease sphincter tone increasing incidence GERD

This reflux is more prevalent in later pregnancy owing to elevation of the stomach by the enlarged uterus, making the use of anesthesia, especially general anesthesia more hazardous because of the increased possibility of regurgitation and aspiration.

Lower incidence of PUD (peptic ulcer disease) may be due to decreased gastric acid secretion delayed

emptying, increase in gastric mucus, and protection of mucosa by prostaglandins

Maternal Physiology in Pregnancy: Digestive Tract Changes

Small bowel : Reduced motility and tone are allow for

more efficient absorption, especially iron

Large Bowel: Decreased transit times allows for both

water and sodium absorption. Increased portal hypertension with

dilation wherever there are porto-systemic venous anastamoses (varices) affecting esophagus, vulva and increase varicose veins and hemorrhoids may lead to ovarian vein thrombosis

Maternal Physiology in Pregnancy: Gastrointestinal Changes Gallbladder

Decreased rate of emptying and hypotonia of the smooth muscle wall

Emptying time is slowed and often incomplete Bile can become thick, and bile stasis Cholesterol saturation is increased while

chenodeoxycholic acid is decreased in bile These changes favor the development of gallstones

Maternal Physiology in Pregnancy: Gastrointestinal Changes

Liver

Liver size and histology are unchanged Serum albumin and total protein decrease

so there is a decrease in the albumin/globulin ratio

Serum alkaline phosphatase increases due to placental and some hepatic production

No change in serum bilirubin, AST, ALT Clinical and laboratory changes mimic

disease states Spider angiomas and palmar erythema

Maternal Physiology in Pregnancy: Urinary System

Anatomic Changes Renal hypertrophy Dilatation renal pelvis/calyces 15mm on the right in 3rd

trimester 5mm on the left. Each kidney increases in length by 1-1.5cm, with a

concomitant increase in weight. The ureters are dilated to 2 cm resulting in hydroureter from: progesterone-induced smooth muscle relaxation causing

hypotonia mechanical compression above the brim of the bony pelvis by

the ovarian vein complex in the suspensory ligament of the ovary

dextorotation of the uterus during pregnancy, may explain why the right ureter is usually more dilated than the left.

Maternal Physiology in Pregnancy: Urinary System Hyperplasia of smooth muscle in distal one-third

of the ureter may cause reduction in the luminal size

The ureters also elongate, widen, and become more curved: there is an increase in urinary stasis

This may lead to infection and predispose to pyelonephritis in the presence of asymptomatic bacteriuria (30%)

Maternal Physiology in Pregnancy: Urinary System Bladder As the uterus enlarges, the urinary bladder is displaced

upward and flattened in the anterior-posterior diameter Bladder vascularity increases and muscle tone decreases,

increasing capacity up to 1500ml. Trigone elevation occurs with increased vascular

tortuousity throughout the bladder leading to microhematuira

Decrease bladder capacity Increased frequency of urinary incontinence

Maternal Physiology in Pregnancy: Urinary System

Renal Hemodynamic Renal blood flow increases 50% . GFR increases 50% (120cc/min180cc/m.) The renal plasma flow rate increases by as much as 25-50%.. Serum Creatinine and BUN levels decrease. Urinary flow and sodium excretion rates in late pregnancy

can be altered by posture, being twice as great in the lateral recumbent position as in the supine position.

Even thought the GFR increased dramatically during pregnancy, the volume of the urine passed each day is not increased.

Maternal Physiology in Pregnancy: Urinary System With the increase in GFR, there is an increase in

endogenous clearance of creatinine. The concentration of creatinine in serum is reduced in

proportion to increase in GFR, and concentration of blood urea nitrogen is similarly reduced.

Glucosuria during pregnancy is not necessarily abnormal, may be explained by the increase in GFR with impairment or exceeding tubular reabsortion capacity for filtered glucose.

Increased levels of urinary glucose also contribute to increased susceptibility of pregnant women to urinary tract infection.

Proteinuria changes little during pregnancy and if more than 300mg/24h is lost, a disease process should be suspected.

Maternal Physiology in Pregnancy: Urinary System Levels of the enzyme renin, which is produced in kidney,

increase early in the first trimester, and continue to rise until term

This enzyme acts on its substrate angiotensinogen, to first form angiotensin1 and then angiotensin2, which acts as a vasoconstrictor

Normal pregnant women are resistant to the pressor effect of elevated levels of angiotensin2 but those suffering from preeclampsia are not resistant, this is one of the some theories to explain this disease.

Maternal Physiology in Pregnancy: Cardiovascular System

As the uterus enlarges and the diaphragm becomes elevated, the heart is displaced upward and somewhat to the left with rotation on its long axis, so that the apex beat is moved laterally. (apparent cardiomegaly on chest x-ray)

Cardiac capacity increases by 70-80mL. This may be due to increased volume or hypertrophy of cardiac

muscle. The size of the heart appears to increase by about 12%. Increase in left ventricular end- diastolic dimension. Increase in left ventricular wall mass c/w mild hypertrophy. Increase in preload with increase capacitance of the systemic

and pulmonary vascular resistances prevenst rise in CVP or wedge pressure.

Grade II-III systolic flow murmurs at left lower sternal border.

Maternal Physiology in Pregnancy: Cardiovascular System

30-35% in CO (CO= SV x HR), reaching its maximum at 20-24 weeks gestation and continuing at this level until term

The increase in output can be as much as1.5L/min over the non pregnant level

HR increases as early as 5 weeks GA Peaks at 32 weeks at 15-20 beats above baseline(20%

increase) Stroke volume increases as early as 8 weeks GA, peaks

at 20 weeks with a 20-30% increase Cardiac output is very sensitive to changes in body

position.

Maternal Physiology in Pregnancy: Cardiovascular System This sensitivity increases with gestational age,

presumably because the uterus impinges upon the inferior vena cava, thereby decreasing blood return to the heart

Because blood pressure either decreases or remain the same during pregnancy and cardiac output increases appreciably, there is good evidence that peripheral resistance( Peripheral resistance equals blood pressure divided by cardiac output) declines markedly.

The elevated venous pressure returns toward normal if the woman lies in the lateral recumbent position.

Maternal Physiology in Pregnancy Position effects on CV system•

Maternal Physiology in Pregnancy: Cardiovascular System Effects of the Labor on the Cardiovascular System

When a patient is the supine position, uterine contractions can cause a 25% increase in maternal cardiac output, a 15% decrease in heart rate, and a resultant 33% increase in stroke volume.

However when the laboring patient is in the recumbent position, the hemodynamic parameters stabilize , with only a 7.6% increase in cardiac output, a 7% decrease in heart rate, and a 7.7% increase in stroke volume

These significant differences are attributable to inferior vena caval occlusion caused by the gravid uterus

Maternal Physiology in Pregnancy: Cardiovascular System During contractions, pulse pressure increases

26% in the supine position but only 6% in the lateral recumbent position.

Important to have laboring patients in the left lateral recumbent position

Maternal Physiology in Pregnancy: Cardiovascular System BP= CO x SVR SVR decreases to a minimum at midpregnancy with a

gradual rise towards term but still 20% lower than non-pregnancy

Decrease SVR secondary to hormonal vasodilatation (progesterone), NO, prostaglandins, ANP

BP changes nadir by midpregancy Diastolic and mean pressure decrease more than the

systolic Increases to baseline in third trimester

Maternal Physiology in Pregnancy: Cardiovascular System

Other cardiovascular changes:Increases in CO, HRDecreases in SVR, PVRNo change in MAP, PCWP, CVP,

Maternal Physiology in Pregnancy: Cardiovascular System Blood Volume ` Increase in the blood volume beginning at 6

weeks and plateaus at 30 weeks The magnitude of the increases varies according

to the size of woman, the number of pregnancies she has had, the number of infants she has delivered, and whether there is one or multiple fetuses

Both plasma volume (50%)and cell mass (30%) increase

Physiologic anemia of pregnancy nadiring at 30 weeks

Maternal Physiology in Pregnancy: Cardiovascular System

By term, the average increase in volume 45-50% The increase is needed for extra blood flow to the

uterus, extra metabolic needs of fetus, and increased perfusion of others organs, especially kidneys

Extra volume also compensate for maternal blood loss delivery

The average blood loss with vaginal delivery is 500ml, cesarean section is 1000ml and C/Hyst 1500 ml

10% drop HCT can be considered post-partum hemorrhage

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Maternal Physiology in Pregnancy: Cardiovascular System

Maternal Physiology in Pregnancy: Cardiovascular System

Blood Volume

(1) Singleton (n=50)

3rd trim. non-preg. % increase

Blood volume 4820 3250 48

RBC volume 1790 1355 32

Hct (%) 37.0 41.7 Pritchard, JA. Changes in blood volume during pregnancy

5th percentile for hemoglobin was 11.0 g/L in the 1st trimester; in the 2nd trimester it was 10.5 g/L and 10.3 g/L in the third trimester

Acta Obstet Gynecol Scand. 2000 Feb;79(2):89-98

Maternal Physiology in Pregnancy: Cardiovascular System Iron Metabolism Absorption in the duodenum in the divalent state Trivalent food source must be converted by ferric

reductase to divalent form Febound transferrintransported to liver, spleen, muscle

and bone marrow incorporated into hemoglobin, myoglobin, ferritin or hemosiderin

1000mg iron requirement, (about 3.5 mg/d) Requirements increase in third trimester Fetus receives Fe through active transport

Maternal Physiology in Pregnancy: Cardiovascular System

With the increase in red blood cells, the need for iron for the production of hemoglobin increases, but Fe supplementation usually not needed before 20 weeks

Fe supplementationFerrous sulfate 20% ( 65mg elemental Fe) Ferrous gluconate 12% (35mg of elemental Fe) and ferrous fumarate 33%(108mg of elemental Fe) ; fumerate and gluconate better absorbed(organic Fe)

For severe anemia: Preparations

Iron Dextran (Imferon, Dexferrum) High rate of serious reaction (requires test dose) Intramuscular or Intravenous Dose based on estimated iron deficits

Maternal Physiology in Pregnancy: Cardiovascular System (Test dose)

[25 mg] [100 ml] [5 min]

[Prescribed dose] [250 to 1000mg](Usually 500 ml NS)

Total dose infusion: infuse over 2 to 6 hours.

Maternal Physiology in Pregnancy: Cardiovascular System

Sodium ferric gluconate (Ferrlecit) Dosing: 125 mg/weekly IV for 8 weeks (total: 1 gram) Much safer than Iron Dextran (no test dose needed)

Iron sucrose (Venofer) Much safer than Iron Dextran (no test dose needed) Dosing: 200 mg IV for 5 doses over 2 week period

Precautions Intravenous iron must be started very slowly Adverse affects: fever, pain, headaches, Myalgias and arthralgias Anaphylaxis

Occurs in 0.61% of patients given Iron Dextran Occurs in 0.04% of patients given ferric gluconate

Maternal Physiology in Pregnancy: Cardiovascular System

Maternal requirements can reach 5-6mg/d in the latter half of pregnancy

If supplemental iron is not added to the diet, iron deficiency anemia will result

If iron is not readily available, the fetus, uses iron from maternal stores.

Thus, the production of fetal hemoglobin is usually adequate even if the mother is severely iron deficient and anemia in the newborn is rarely a problem

Maternal iron deficiency more commonly may cause preterm labor and late spontaneous abortion,

Maternal Physiology in Pregnancy: Cardiovascular System White Blood Cells

The total blood leukocyte count increases during pregnancy from a pre-pregnancy level of 4300-4500/mL to 5000-12000/mL in the last trimester, although counts as high as 16000/mL have been observed in the last trimester

Counts as high as 25000-30000/mL have been noted in a normal patient during labor

Lymphocyte and monocyte numbers stay the same throughout pregnancy; polymorphonuclear leucocytes are the primary contributors to the increase.

Maternal Physiology in Pregnancy: Cardiovascular System Platelets

Progressive decline in count from 1st-3rd trimester. Increased platelet destruction. Plts range between 70-150,000, gestational

thrombocytopenia of pregnancy Burrows @Kelton reported an 8% prevalence.

Diagnosis of exclusion: PIH/HELLP, ITP, viral disease, HIV, autoimmune disease, ie lupus.

Maternal Physiology in Pregnancy: Cardiovascular System Other Hematologic Changes

Leukocytosis secondary to increase neutophils estrogen and cortisol induced

Altered immune status, immunocompromised Paradoxical decline of immunoglobins A,G,M Only IgG crosses the placenta

Maternal Physiology in Pregnancy: Cardiovascular System Coagulation System Hypercoaguable state Increased venous stasis lead to vessel wall injury Changes in the coagulation cascade Increases in factors I,VII,VIII, IX and X Unchanged or mildly increasedfactors II, V, XII Decrease in factors XI, XIII Decrease in fibrinolysis with decreased plasminogen

activator Increase in factor I (fibrinogen) causes elevated sed rate Decrease in protein S but no change in protein C and

antithrombin III. Activated protein C decreases

Maternal Physiology in Pregnancy: Cardiovascular System Fibrinolytic activity is depressed during pregnancy and

labor, although the precise mechanism is unknown The placenta may be partially responsible for this

alteration in fibrinolytic status Plasminogen levels increase concomitantly with

fibrinogens levels, causing an equilibration of clotting and lysing activity

Maternal Physiology in Pregnancy:Respiratory System Anatomic and Physiologic Changes Pregnancy produces

changes that affect respiratory performance Early in pregnancy, capillary dilatations occurs

throughout the respiratory tract, leading to engorgement of the nasopharnyx, larnyx, trachea, and bronchi

This causes the voice to change and makes breathing though the nose difficult.

Upper respiratory tract hyperemia and edema induced by estrogen leading to nasal stuffiness and epistaxis

Chest X-rays reveal increased vascular makings in the lungs.

Maternal Physiology in Pregnancy:Respiratory System As the uterus enlarges, the diaphragm is elevated as much

as 4cm, but elevation of the diaphragm does not impede its movement.

The rib cage is displaced upward and widens, increasing the lower thoracic diameter by 2cm and the thoracic circumference by up to 6cm.

Chest circumference expands 5-7 cm Subcostal angle increases from 68 to 103 degrees Respiratory muscle function is not affected by pregnancy Abdominal muscles have less tone and are less active

during the pregnancy, causing respiration to be more rather than less diaphragmatic.

Maternal Physiology in Pregnancy:Respiratory System Elevation of the diaphragm decreases the volume of the

lungs in the resting state, reducing TLC by 5% and FRC by 20%

FRC mainly decreased by RV Vital capacity does not change Chronic hyperventilation progesterone induced Minute volume is increased Tidal volume is increased Respiratory rate is unchanged( Increased early in the first

trimester)

Maternal Physiology in Pregnancy:Respiratory System Dead volumes increase owing to relaxation of the

musculature of conducting airways. Tidal volumes increases gradually(35-50%)as pregnancy

progresses. Total lung capacity is reduced (4-5%) by the elevation of

the diaphragm. Functional residual capacity, residual volume, and

respiratory reserve volume all decrease by about 20%. Larger tidal volume and smaller residual volume cause

increased alveolar ventilation (about 65%) during pregnancy.

Inspiratory capacity increases 5-10%.

Maternal Physiology in Pregnancy:Respiratory System Functional respiratory changes include a slight increase in

respiratory rate, a 50% increase in minute ventilation, a 40% increase in tidal volume

A progressive increase in oxygen consumption of up to 15-20% above non-pregnant levels by term.

With the increase in respiratory tidal volume associated with a normal respiratory rate, there is an increase in respiratory minute volume of approximately 26%

. As the respiratory minute volume increases, hyperventilation of pregnancy occurs, causing a decrease in alveolar CO2

Maternal Physiology in Pregnancy:Respiratory System

This decrease lowers the maternal blood CO2 tension; however alveolar oxygen tension is maintained within normal limits.

Maternal hyperventilation is considered a protective measure that prevents the fetus from the exposure to excessive levels of CO2.

Because this decrease in FRC occurs without a concomitant change in dead space, there is little residual dilution and, therefore, presumably more efficient gas exchange.

Maternal Physiology in Pregnancy:Respiratory System Spirometry: the most common of the Pulmonary Function

Tests(PFTs), measuring lung function, specifically the measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled.

FEV1 (forced expiratory pressure in 1 second), 80-100% of average values are considered normal and is unchanged

Peak Expiratory Flow: is the maximal flow (or speed) achieved during the maximally forced expiration initiated at full inspiration, measured in liters per minute, also unchanged

Lungs Function in Pregnancy•

Lungs in late pregnancy

•

Maternal Physiology in Pregnancy:Respiratory System: Gas Exchange Hyperventilation leads to deceased PCO2 Increases CO2 gradient between fetus and mother Chronic respiratory alkalosis Compensatory metabolic acidosis 20-40% increase in maternal oxygen

consumption Normal arterial blood gas values Ph= 7.4-7.45

PCO2= 28-32 PO2= 101-106 HCO3= 18-21

Maternal Physiology in Pregnancy

Metabolism As the fetus and placenta grow and place increasing demands

on the mother, phenomenal alterations in metabolism occur The most obvious physical changes are weight gain and

altered body shape Weight gain is due not only to the uterus and its contents but

also to increase breast tissue, blood and water volume in the form of extravascular and extracellular fluid

Deposition of fat and protein and increased cellular water are added to the maternal stores

The average weight gain during pregnancy is 12.5Kg. (23-25 lbs)

Maternal Physiology in Pregnancy During normal pregnancy, approximately 1000g of weight

gain is attributable to protein Half of this is found in the fetus and the placenta, with

the rest being distributed as uterine contractile protein, breast glandular tissue, plasma protein, and hemoglobin

Total body fat increases during pregnancy, but the amount varies with total weight gain

During the second half of pregnancy, plasma lipids increase , but triglycerides, cholesterol and lipoproteins decrease soon after delivery

The ratio of low density lipoproteins to high density lipoproteins increases during pregnancy

Maternal Physiology in Pregnancy Body Water Metabolism Condition of chronic water overload Active Na+ and water retention 1. Changes in osmoregulation 2. Renin-angiotensin system Body water increase 6.5L 8.5L 1. 1500 cc increase in blood volume 2. RBC increase ~400cc Elevation of maternal CO

Maternal Physiology in Pregnancy Osmoregulation Na+ retention increases 900 mEq but serum Na+

decreases 3-4 mmol/l Plasma osmolality decreases 10 mOsm/kg Enhanced tubular reabsorption of Na+ secondary

to aldosterone, estrogen and deoxycorticosterone Increased GFR and Atrial Natriuretic Peptide

favor Na+ excretion

Maternal Physiology in Pregnancy Skeletal Changes: Calcium metabolism Maternal total calcium levels decline due to decreased

albumin bound concentration Serum ionized level remains unchanged Increased intestinal absorption occurs in first trimester,

actively transported across the placenta Maternal serum phosphate levels are unchanged PTH levels remain unchanged Elevated levels of vitamin D allow for increase Ca++

absorption Calcitonin levels rise to preserve maternal skeleton

Maternal Physiology in Pregnancy Skeletal and Postural Changes Lordosis of pregnancy~ progressive increase in

anterior convexity of the lumbar spine, preserves center of gravity

Ligaments of the symphysis and sacroiliac joints loosen during pregnancy due to relaxin

Maternal Physiology in Pregnancy Endocrine Changes Thyroid Physiology Euthyroid state Increase in thyroxine-binding globulin Decrease in circulating pool of extra-thyroidal

iodide Slight thyromegaly Free T4 and Free T3 remain normal Small amounts of TRH /T4 cross the placenta Fetal thyroid active by 12 weeks gestation

Maternal Physiology in Pregnancy Endocrine Changes Adrenal function Increases in corticosteroid-binding globulin Increases in free cortisol Zona fasciculata is increased Marked increase in CRH from placental sources Delayed plasma clearance of cortisol due to renal

changes Resetting of hypothalamic-pituitary sensitivity to

cortisol feedback on ACTH production

Maternal Physiology in Pregnancy Endocrine Changes Pituitary gland enlarges due to proliferation of

prolactin-secreting cells Enlargement makes it more susceptible to

alterations in blood flow Prolactin levels are increased (ten times higher at

term) to prepare breasts for lactation

Maternal Physiology in Pregnancy Endocrine Changes

Pancreas and Fuel Metabolism Physiologic glucose intolerance to insure

continuous transport of nutrients from mother to fetus

Fasting hypoglycemia Postprandial hyperglycemia Hyperinsulinemia

Insulin Response after a Meal

Glucose Response after a Meal

Maternal Physiology in Pregnancy Fuel Metabolism Pregnant prolonged fasting Increased utilization of fat stores Lipolysis generates glycerol, fatty acids and

ketones for gluconeogenesis and fuel More HPL, less insulin results in increased

utilization of fat stores Maternal response to starvation hypoglycemia,

hypoinsulinemia , hyperlipidemia, hyperketonemia

Maternal Physiology in Pregnancy Fuel Metabolism Maternal response to feeding Hyperglycemia Hyperinsulinemia Hyperlipidemia Resistance to insulin Insulin secretion increases throughout Insulin resistance increases to 50-80% in third

trimester Borderline pancreas function leads to GDM

Maternal Physiology in Pregnancy Endocrine Changes Diabetogenic effects of pregnancy HPLlipolytic and anti-insulin( Cortisol Prolactin

Estrogen and Progesterone Fetal glucose levels are 20 mg/dl less than

maternal values Placental glucose transport is carrier mediated

facilitated transport that is energy independent

Maternal Physiology in Pregnancy Fuel and Metabolism Lipids and lipoproteins increase in

pregnancy Total cholesterol, LDL, HDL and

triglycerides all increase Necessary as precursors for steroiodgenesis Does not appear to lead to atherosclerosis

unless pre-existing hyperlipidemia

Placental Transport of Nutrients

Maternal Physiology in Pregnancy

Integumental Changes

Hyperpigmentation 90% of pregnancies

Localized to areas of increased melanocytes

Choasma of pregnancy 70% of women in all races

Linea alba…Linea nigra Up to 30% of changes can persist

Maternal Physiology in Pregnancy Integumental Changes

Hair Changes Mild hirsutism is common Excessive virilization

should prompt investigation for androgen-secreting tumors

Normal pregnancy increases amount of hair in anagen phase(growth)

Postpartum, telogen effluvium may occur with increased amount of hair in resting phase which leads to loss

Maternal Physiology in Pregnancy Ocular Changes Increased thickness of the cornea secondary to

fluid retention, this edema induces causing a 3% increase

Affects contacts Decreased intraocular pressure Glaucoma improves Minimally decreases visual fields

Maternal Physiology in Pregnancy So you see there are extensive

changes in maternal physiology that occur in pregnancy

Be careful in interpretations of what are normal pregnancy changes, especially when parameters like lab values represent the non-pregnant state

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