OB Exam 1 - Maternal Physiologic Changes in Pregnancy

How do the *breasts change during pregnancy*?

Breast size increases rapidly during first 8 weeks of pregnancy then steadily thereafter. -Total enlargement is 25-50% -Blood flow to the breasts increases to support lactation -Colostrum produced during latter portion of pregnancy: thick yellow fluid expressed from the nipples -Ultimately lactation depends on the following hormones: estrogen, progesterone, prolactin, human placental lactogen, cortisol, and insulin

Why does *constipation* commonly occur during pregnancy?

Compression of bowel by expanding uterus, reduced mobility and increased water absorption from colon during pregnancy

What *thyroid* changes occur during pregnancy?

Several changes occur in thyroid regulation but the *net effect is a euthyroid state* (no NET change in thyroid function)

What are the source of some *dietary cravings* that occur during pregnancy?

Some cravings may be the result of patient perception that they will decrease nausea. -Pica: ice, starch, clay

While edema is normal during pregnancy, why would *sudden edema to the hands and face* be worrisome?

Some edema to the hands/face is normal during pregnancy, but if this occurs suddenly, can be a sign of *preeclampsia*.

When do *fetal gonads develop* and when do *other genital organs develop*?

Testicular/ovarian differentiation begins approximately at 8 weeks gestation Other genital organ development is *dependent on hormones and develop independent of testes/ovaries*. >>> future development requires estrogen and testosterone

At how many weeks gestation does the *first trimester* end?

The 1st trimester is through *13 completed weeks and 6 days of gestation*

What *cardiovascular physical exam findings* may be seen in normal pregnant women?

*ALL of these physical exam findings are a result of increased blood volume*: 1. Increased splitting of S1 and S2 with inspiration 2. Low grade systolic ejection murmur over pulmonary and tricuspid areas 3. S3 present in most by the 3rd trimester 4. Mammary souffle present in some by 3rd trimester (hum heard over the breast d/t increased blood flow to breasts) 5. Distended neck veins are common and normal

How do BUN and Creatinine lab values change during pregnancy?

*BUN and Creatinine decrease during pregnancy*

What *eye/visual changes* occur in pregnancy?

*Blurred vision* occurs due to increased thickness of the cornea associated with fluid retention and decreased intraocular pressure. -Occurs during first 6-8 weeks then regresses 6-8 weeks post-partum. -Changes in glasses/contact prescriptions should NOT be encouraged during pregnancy. >>>But can do ophthalmology eval just in case.

What *physiologic cardiovascular changes* are seen during pregnancy?

*Increased cardiac output* (30-50% increase) -*First half of pregnancy*: increased SV secondary to increased blood volume and decreased vascular resistance -*Second half of pregnancy*: increased maternal heart rate (10-18 bpm over normal) NOTE: late in pregnancy, CO may *decrease* because of compression of inferior vena cava especially when supine.

Which respiratory volumes and capacities *decrease* as a result of pregnancy?

*Mostly decrease as a result of elevation of the diaphragm*: -Residual volume (d/t elevated diaphragm) -Functional residual capacity (elevated diaphragm) -Total lung capacity (elevated diaphragm) -Expiratory reserve volume (d/t increased respiratory capacity)

How does *blood pressure* normally change during pregnancy?

-BP typically falls slightly early in gestation and is usually *10 mmHg below baseline in the second trimester* declining to a mean of 105/60 mmHg. -In the third trimester, *the diastomic BP gradually increases and may normalize to nonpregnant values by term*

What are the characteristics of *fetal hemoglobin* and where does it come from?

-Fetal hemoglobin has higher affinity for oxygen than maternal hemoglobin. -This allows fetal hemoglobin to *take O2 from the maternal hemoglobin* >> we want this to happen! -The maternal blood takes fetal CO2. This decreases maternal blood pH. This shifts the fetal oxygen dissociation curve to the left as pH increases which further increases its ability to hold onto oxygen.

How do pregnant women's hair change during pregnancy?

-More follicles in growth phase during pregnancy -But, significant hair loss 2-4 months after pregnancy >>>Reassurance that normal growth will resume in 6-12 months

How does *carbohydrate metabolism* change during pregnancy?

-Reduced tissue response to insulin in pregnancy -Hepatic glycogen synthesis and storage is inhibited: net result in a hyperglycemic state postprandially -*Fetus and placenta uses glucose as primary energy source*: During maternal fasting hypoglycemia of the mother develops.

When does the *fetal kidney* become functional and what is its function during pregnancy?

-The fetal kidney becomes functional *in the second trimester* producing *dilute, hypotonic urine*. -This urine is the primary source of *amniotic fluid by the second trimester*

What is the role of the *fetal liver* during pregnancy?

-The fetal liver is *slow to mature* -Most bilirubin is eliminated through the placenta by the maternal liver -Hepatic production coagulation factors is often *deficient due to vitamin K deficiency*. Routine administration of vitamin K at the time of birth prevents newborn hemorrhagic disorders.

What are *pulmonary symptoms* seen in pregnancy?

1. *Dyspnea* of pregnancy seen in 60-70%: probably a physiologic response to low CO2 levels. >>>Ie. not really SOB, just feel that way because CO2 is low 2. *Mucosal hyperemia*: increase blood flow to nasal passageways causing nasal stuffiness

What *hematologic symptoms and physical exam findings* can be seen in pregnant women?

1. *Edema*: results from decreased oncotic pressure of plasma *decreased osmolality) secondary to the fact that *plasma volume increases to a greater extent than RBC mass* >>>Edema noted primarily in dependent portions of the body/feet. (can occur to lesser extent in hands/face. Sudden edema in hands/face can be a sign of *preeclampsia*)

What are the 4 main physiologic/anatomic changes in the *gastrointestinal system* that occur during pregnancy?

1. *GERD*: progesterone decreases LES tone and decreases GI motility. Enlarging uterus increases intragastric pressure. 2. *Constipation*: decreased GI motility 3. *Increased risk of gall stone disease*: estrogen increases secretion of cholesterol into bile, Progesterone decreases the secretion of bile acids into bile, Bile becomes over-saturated with cholesterol, There is decreased contractility of the gallbladder. 4. *Increased risk of cholestasis of pregnancy*: Decreased rate of transportation of bile salts into the hepatic ducts which can lead to increased concentration of bile salts in the blood >>> which can lead to miscarriage.

What 2 *physical exam signs of GI changes* are seen in pregnancy?

1. *Gingival disease*: gums become more edematous and soft - *epulis gravidarum (granulomas in the mouth)* can develop 2. *Hemorrhoids*: due to constipation and elevated venous pressures - increased pelvic blood flow and enlarged uterus pressing on IVC.

What 3 *hematologic changes* occur during pregnancy?

1. *Increased RBC volume*: leads to increased total oxygen-carrying capacity. O2 dissociation curve shifts to the *left* due to *alkalosis*. Blood volume increases by ~35% by term. Adequate iron availability is essential. 2. *WBC count increases*: 9K-15K normal range by third trimester 3. *Increase in production of clotting factors, a decrease in protein S, an resistance to activated protein C, and decreased fibrinolysis*: contribute to hypercoagulability during pregnancy. Risk of VTE doubles during pregnancy; this increases to 5.5 time above normal risk during the time of delivery. INR and PTT decrease slightly but remain in the normal range.

What are the 2 main causes/sources of the cardiovascular changes that occur during pregnancy?

1. *Increased blood volume during pregnancy*: increased intravascular volume due to resetting of thirst threshold and secreting ADH at lower osmolalities. Increased RBC mass b/c increased erythropoietin secretion. 2. *Decreased systemic vascular resistance*: Decreased responsiveness to angiotensin II and norepinephrine. Estrogen, progesterone, BHCG, and relaxin are all though to lead to *vasodilation*.

What *renal system symptoms* present during pregnancy?

1. *Increased urinary frequency*: (also nocturia) always need to be vigilant for UTIs still. 2. *Stress incontinence*: often confused with premature rupture of membranes -Increased incidence of UTIs due to stasis in ureters and bladder -Changes in diagnostic tests: *BUN and Creatinine decrease during pregnancy*

What *physiologic changes* occur to the renal system during pregnancy?

1. *Increases in renal blood flow*: results in increased glomerular filtration rate which leads to an increased exposure of various solutes 2. *Impaired tubular function*: decreased reabsorption of glucose, amino acids, and beta macroglobulin. >>>Trace glucose in the urine during pregnancy is NORMAL

What 4 *reproductive tract changes* occur during pregnancy?

1. *Vulvar varicosities are common* 2. *Thick profuse vaginal discharge*: leukorrhea of pregnancy > increase in vaginal transudation, hormonal stimulation of vaginal epithelium 3. *Cervical ectropion*: the epithelium of the endocervix everts onto the ectocervix. 4. *Uterus*: Increase in weight from 70g to 1,100 g at term > hypertrophy of myometrial cells. Cavity volume increases from 10 mL up to 5 mL (volume capacity of the uterus)

What *anatomical changes* occur in the *respiratory system* during pregnancy?

1. Diaphragm elevated ~ 4 cm by term 2. Chest circumference increases slightly

On which hormones does lactation depend?

1. Estrogen 2. Progesterone 3. Prolactin 4. Human placental lactogen 5. Cortisol 6. Insulin

What *GI lab changes* occur during pregnancy?

1. Increased alkaline phosphatase: placenta produces it 2. Increased serum cholesterol: a result of excess estrogen 3. Decreased serum albumin: albumin production actually increases but because of increased plasma volume, levels are lower (dilution)

What 7 *GI symptoms* may occur during pregnancy?

1. Increased appetite with increased caloric intake of ~200 kcal/day 2. Nausea and vomiting of pregnancy 3. Hyperemesis gravidarum 4. Dietary cravings 5. Dietary/olfactory aversions (more common than cravings) 6. Constipation 7. Pruritus (COMMON during pregnancy)

What *musculoskeletal* changes occur during pregnancy?

1. Lumbar lordosis increases 2. Exacerbation of hernia defects: umbilical hernia COMMON in pregnancy, diastasis recti can occur too. 3. Laxity of ligaments: most of the changes during pregnancy >>>Result of progesterone and relaxin. Relaxin is produced by the placenta >>>Separation of the pubic symphysis at 28-30 weeks.

What *physiologic changes* occur in the *respiratory system* during pregnancy?

1. PaO2 is slightly *increased* (because you take deeper breaths during pregnancy) 2. *Progesterone increases central chemoreceptor sensitivity to CO2 which leads to increased respiratory drive and a decreased pCO2*

What *skin changes* occur during pregnancy?

1. Spider angiomas 2. Palmar erythema 3. Striae gravidarum (stretch marks) 4. Hyperpigmentation 5. Sweating/sebum production 6. Hair growth

What 3 *anatomic cardiovascular changes* occur normally in pregnancy?

1. The heart is displaced upward and to the left and is more horizontal >>> PMI moved to the 4th ICS and displaced laterally 2. Ventricle muscle mass increases 3. LA and LV increase in size

What *anatomic changes* occur to the kidney during pregnancy?

1. The kidneys grown in size by approximately 1 cm in length 2. Progesterone decreases bladder tone leading to increased residual volumes 3. As uterus enlarges, bladder capacity decreases >>>>Together, these cause *increased risk of UTI during pregnancy*

What affects does *increased estrogen during pregnancy* have on the *skin*?

1. Vascular spiders (spider angiomas): upper torso, face, arms (regress after delivery) 2. *Palmar erythema* (50%): regresses after pregnancy

At how many weeks gestation does the *second trimester* end?

2nd trimester is *14 weeks through 27 week and 6 days gestation*

Why do *alkaline phosphatase* levels normally increase during pregnancy?

Because the placenta produces alkaline phosphatase.

At how many weeks gestation does the *third trimester* occur?

3rd trimester occurs from *28 weeks through 40 weeks (0 days) of completed gestation

What *pulmonary lab* abnormalities might be seen in pregnant patients?

ABG: PCO2 is typically *low* (27-32). This is at least partially compensated for by an increased renal secretion of bicarbonate (bicarb levels will be *low*)

What are *striae gravidarum* and how are they treated?

AKA striae distensae (stretch marks) -Often found on lower abdomen, breast, buttocks, thighs -NOT the result of weight gain -Permanent - although FADE with time and usually become hypopigmented *Treatment*: Topical retinoids (NOT during pregnancy) MAY help with appearance as can laser therapy (expensive and not covered by insurance)

What are current recommendations for *iron supplementation* in pregnant women?

Adequate iron availability is *essential* to increase maternal RBC volume during pregnancy. -Current recommendations are for *supplementation of 30 mg iron per day* (present in most prenatal vitamins) -If woman is anemic, should receive *30-120 mg elemental iron per day until anemia is corrected*.

How does the fetus get *immunity*?

Antibodies (*only IgG*) cross the placenta and confer passive immunity to the fetus. -The fetal immune system develops gradually throughout pregnancy.

How does venous return changes as pregnancy progresses?

As pregnancy progresses there is impaired venous return as the uterus compresses the IVC when patient is supine. -Lie on side as opposed to back

How much does the *blood volume* increase during pregnancy?

Blood volume increases by ~35% by term.

What is important to know about *assessing blood pressures in pregnancy women*?

BP measurements should be done with the woman in the same position at every time. >>>In general, should be done in seated or slightly reclining position. >>>BP will be lower if patient is supine, so do NOT check BP with patient supine.

How do *blood tests* and *clotting times* change during pregnancy?

During pregnancy, the *normal range of several hematologic indices change*. -Physiologic anemia occurs: >>>*Hgb: ~14 g/dL is norma* >>>*Plasma volume increases more than red cell volume*: <11 mg/dL is anemia in 1st and 3rd trimesters. <10.5 mg/dl in 2nd trimester >>>*Elevated WBC*: up to 30,000/L can be normal in labor and following delivery -*Clotting times are unchanged*

How does *protein metabolism* change during pregnancy?

During pregnancy, there is *increased protein intake and utilization* (use up more protein during pregnancy)

In what body system do the *earliest and most dramatic changes in maternal physiology* occur?

Earliest and most dramatic changes in maternal physiology are *cardiovascular*.

How does the level of immunoglobulins compare between human colostrum, human breast milk, and cow's milk?

Human colostrum has by far the MOST immunoglobulin (IgA mostly). (19 times more than cow's milk and even more than human breast milk)

How does sweating/sebum production change during pregnancy?

Increase during pregnancy and can lead to acne.

How does the oxygen dissociation curve shift during pregnancy and why does this occur?

Increase in RBC volume during pregnancy causes increase in total O2 carrying capacity. >>Oxygen dissociation curve *shifts to the left due to alkalosis during pregnancy*

How many more calories per day should a healthy pregnant woman ingest?

Increased caloric intake of ~200 kcal per day.

How is *minute ventilation* affected in pregnancy?

Increases because of *increased tidal volume, which is larger because of increased drive secondary to progesterone*.

Why does *pruritus* often occur during pregnancy?

Intrahepatic cholestasis leading to increased serum bile acid concentrations can lead to severe pruritus without skin lesions. >>>Itching is very COMMON during pregnancy

What accounts for increased *laxity of ligaments* during pregnancy?

Laxity of ligaments: most of the changes during pregnancy >>>Result of progesterone and relaxin. Relaxin is produced by the placenta >>>Separation of the pubic symphysis at 28-30 weeks.

Is an S4 or diastolic murmur normal in pregnancy?

NO. S4 or diastolic murmur is never normal. -Patients may have S3 or low grade systolic ejection murmurs normally.

What is the typical time of onset and causes of *nausea and vomiting of pregnancy*?

Nausea and vomiting begins by ~4-8 weeks of pregnancy and abates by ~14-16 weeks. -Cause of nausea is *unknown*, but believed to be related to increased levels of progesterone and HCG, and increased smooth muscle relaxation of the stomach.

What changes to the *pulmonary physical exam* occur during pregnancy?

No change in pulmonary exam during pregnancy

What is the normal affect of pregnancy on *cardiac output*?

Normally, cardiac output *increases during pregnancy*: -Increase in SV in first half of pregnancy and Increase in HR in second half of pregnancy. BUT, late in pregnancy, CO may *decrease* because of compression of inferior vena cava especially when supine.

What are the basic routes of *fetal blood circulation*?

Oxygenation of fetal blood occurs in the *placenta instead of the fetal lungs*. 1. *Umbilical vein* carries oxygenated blood to the fetus: Umbilical vein enters the liver portal vein system of the fetus >> one branch goes toward the left lobe of the liver but feeds into the inferior vena cava and becomes origin of ductus venosus. Other branch goes to right lobe of river. 2. *Foramen ovale*: Right atrium to left atrium 3. *Ductus arteriosus*: from pulmonary artery to aorta

What are the 4 *functions of the placenta*?

Placenta is an organ of pregnancy. 1. *Respiratory exchange*: oxygen uptake by fetus and CO2 excretion by simple diffusion. 2. *Metabolite exchange*: Glucose received by placenta and fetus by facilitated diffusion. Amino acids are actively transported 3. *Hormone synthesis*: placenta produces TONS of hormones: produces estrogen, progesterone, hCG and hPL and many others. 4. *Hormone regulation*

How does *lipid metabolism change* during pregnancy?

Pregnancy leads to an *increase in circulating concentrations of lipids, lipoproteins, and apolipoprotiens*. -During early pregnancy, fat storage in central area predominates -Later in pregnancy, lipolysis predominates - triggered by maternal hypoglycemia during fasting: the elevated lipids circulating serve as fuel.

Why/how does *insulin resistance* occur during pregnancy?

The placenta secretes all of the following hormones all of which contribute to a relative insulin resistance during pregnancy: -Growth hormone -Corticotropin releasing hormone -Placental lactogen

How/why is the *antigenically dissimilar fetus not rejected by the mother* during pregnancy?

The placenta: -Keeps *maternal and fetal vascular systems separate*. -Produces hormones that *blunt the maternal immune response LOCALLY* -The syncytium of the trophoblast doesn't have extracellular spaces so it is difficult for immune cells to get through it. Antibodies cross the placenta: -Only IgG-it confers *passive immunity to the fetus* -Fetal immune system develops gradually during pregnancy

What portion of the cardiac output goes to the *uterus* during pregnancy and why is this important?

The uterus receives an increasing percentage of the cardiac output as the pregnancy progresses - nearing 20% at term (notable because of risk of hemorrhage

What is *hyperpigmentation* that occurs in pregnancy and where does it typically occur?

There is some degree of hyperpigmentation of the skin in ALL women during pregnancy. -Sites: umbilicus, perineum, linea alba (becomes linea nigra) -Cholasma: "mask of pregnancy" may never completely disappear (aka melasma) -Moles: can increase in size/color but return to normal after pregnancy

How is *inspiratory capacity* affected by pregnancy?

This *increases because deeper breaths occur in pregnancy from progesterone*

How is *expiratory reserve volume* affected by pregnancy?

This decreases because of *increased tidal volume*

What is *linea nigra*?

This is darkening of the skin area over the linea alba in the abdomen that occurs during pregnancy

What is *melasma*?

This is hyperpigmentation of the face, cheeks, nose, and chin that can occur during pregnancy.

What is *total lung capacity* and how is it affected by pregnancy?

Volume of lungs at maximal inhalation. -This decreases slightly in pregnancy because of *elevated diaphragm*

What is *hyperemesis gravidarum*?

Vomiting in pregnancy that is severe enough to produce any of the following: *dehydration, weight loss, alkalosis, or hypokalemia*.

What is lung *functional residual capacity* and how is it affected by pregnancy?

What's left after a normal exhalation. -This decreases in pregnancy because *tidal volume increases and because residual volume decreases*.

What is *lung residual volume* and how is it affected by pregnancy?

What's left after maximal exhalation. -This decreases in pregnancy because of *elevated diaphragm*