Maternal Physiologic Adaptations to Pregnancy

Question 1

Physiologic Changes During Pregnancy

Answer 1

• Skin
• Cardiovascular
• Hematologic
• Respiratory
• Gastrointestinal
• Genitourinary
• Neurologic
• Endocrine

Question 2

Skin

Answer 2

Increased pigmentation of perineum and areola, chloasma (pigmentation changes under eyes and on bridge of nose), linea nigra (midline abdominal pigmentation)
Other: spider angiomas, palmar erythema due to increased estrogen, striae gravidarum due to connective tissue changes

Question 3

Cardiovascular

Answer 3

Hyper-dynamic circulation
Increased CO, HR, and blood volume
Decreasedbloodpressure duetodecreasedPVRanddecreasedvenousreturnfromenlarginguterus compressing IVC and pelvic veins
Increased venous pressure leads to risk of varicose veins, hemorrhoids, leg edema

Question 4

Hematologic

Answer 4

Hemodilution causes physiologic anemia and apparent decrease in hemoglobin and hematocrit Increased leukocyte count but impaired function leads to improvement in autoimmune diseases Gestational thrombocytopenia: mild (platelets >70,000/μL) and asymptomatic, normalizes within 2-12 wk following delivery
Hypercoagulable state: increased risk of DVT and PE but also decreased bleeding at delivery

Question 5

Respiratory

Answer 5

Increased incidence of nasal congestion and epistaxis
Increased O2 consumption to meet increased metabolic requirements
Elevated diaphragm (i.e. patient appears more “barrel-chested”)
Increased minute ventilation leads to decreased CO2 resulting in mild respiratory alkalosis that helps CO2 diffuse across the placenta from fetal to maternal circulation
No change in VC and FEV1
Decreased TLC, FRC, and RV

Question 6

Gastrointestinal

Answer 6

GERD due to increased intra-abdominal pressure and progesterone (causing decreased sphincter tone and delayed gastric emptying)
Increased gallstones due to progesterone causing increased gallbladder stasis
Constipation and hemorrhoids due to progesterone causing decreased GI motility

Question 7

Genitourinary

Answer 7

Increased urinary frequency due to increased total urinary output
Increased incidence of UTI and pyelonephritis due to urinary stasis (see Urinary Tract Infection, OB29) Glycosuria that can be physiologic especially in the 3rd trimester; must test for GDM
Ureters and renal pelvis dilation (R>L) due to progesterone-induced smooth muscle relaxation and uterine enlargement
Increased CO and thus increased GFR leads to decreased creatinine (normal in pregnancy
35-44 mmol/L), uric acid, and BUN

Question 8

Neurologic

Answer 8

Increased incidence of carpal tunnel syndrome and Bell’s palsy

Question 9

Endocrine

Answer 9

Thyroid
Adrenal
Calcium

Question 10

Endocrine - Thyroid

Answer 10

moderate enlargement and increased basal metabolic rate Increased total thyroxine and thyroxine binding globulin (TBG) Free thyroxine index and TSH levels are normal

Question 11

Endocrine - Adrenal

Answer 11

maternal cortisol rises throughout pregnancy (total and free)

Question 12

Endocrine - Calcium

Answer 12

decreased total maternal Ca2+ due to decreased albumin
Free ionized Ca2+ (i.e. active) proportion remains the same due to parathyroid hormone (PTH), results in increased bone resorption and gut absorption, increased bone turnover (but no loss of bone density due to estrogen inhibition)