Pregnancy

Physiological changes during pregnancy

�?Oxygen consumption (by approx. 20%)
�?Intraabdominal pressure through uterine growth �?dyspnea (the diaphragm is displaced upwards �?�?total lung capacity, residual volume, functional residual capacity, and expiratory reserve volume)
Progesterone stimulates the respiratory centers in the brain �?hyperventilation (to eliminate fetal CO2 more efficiently) �?physiological, chronic compensated respiratory alkalosis
- Ventilation is increased primarily �?Tidal volume �?�?minute ventilation
  - Elevated progesterone levels trigger a sensation of shortness of breath and stimulate the hypothalamus to increase respiratory drive.
  - Facilitated by increased diaphragmatic excursion and hormone-induced laxity of the intercostal muscles that allows for enlargement of the thoracic cavity (although the expanding uterus displaces the resting position of the diaphragm upward, diaphragmatic excursion is not impaired).
- �?PCO2 (�?30 mm Hg)
- Slight increase in respiratory rate

�?Renal plasma flow �?�?GFR �?�?BUN and creatinine
- Increased cardiac output leads to increased renal perfusion.
- Therefore, serum creatinine levels considered normal in nonpregnant patients (eg, 1.0 mg/dL) represent significant renal dysfunction in this population.
�?Glucose levels in urine: Increased glomerular filtration results in overload of the glucose carrier responsible for its resorption.
Mild proteinuria: Increased GFR and glomerular permeability to albumin increases protein excretion.

�?Plasma volume �?�?hematocrit, especially towards the end of pregnancy (30�?4th week of gestation) �?dilutional anemia (hemoglobin value rarely drops below 11 g/dL)
Hypercoagulability is due to an increase in fibrinogen, factor VII, and factor VIII and a decrease in protein S (reduces the risk of intrapartum blood loss).
- Increased estrogen and progesterone levels
�?Platelet count �?gestational thrombocytopenia
�?RBC mass (increases from 8�?0th week of gestation until the end of pregnancy)
�?Iron and folate levels due to increased vitamin and mineral requirements

Human placental lactogen (hPL): a hormone synthesized by syncytiotrophoblasts of the placenta, which promotes the production of insulin.
- Increased maternal glucose levels: allows glucose to freely cross the placenta for consumption by the fetus for energy
  - Causes insulin resistance
- Increased maternal proteolysis: provides a readily available supply of amino acids for the fetus
- Increased maternal lipolysis: leads to increased free fatty acids and ketones to provide energy to the mother, preserving glucose and amino acids for the fetus

�?Salivation
�?Lower esophageal sphincter tone �?gastroesophageal reflux
�?Motility �?constipation and bloating
- Progesterone decreases colonic smooth muscle activity and decreases fasting MMCs (migrating myoelectric complex) in the small intestine
- Gravid uterus mechanically impedes small intestine transit
Gallbladder stasis �?gallstones
- Estrogen increases cholesterol secretion into bile
- Progesterone reduces gallbladder motility
Hemorrhoids
- Gravid uterus increases venous pressure

�?Body weight �?forward shift in center of gravity �?�?lumbar lordosis
�?Intraabdominal pressure �?diastasis recti; meralgia paresthetica
Relaxation of the pelvic girdle ligaments and symphysis pubis �?pelvic girdle pain, coccygeal pain
- Due to progesterone and relaxin
  - Relaxin: a vasodilating hormone secreted by the corpus luteum, and later, by the placental and decidual membranes. Increases endothelial nitric oxide secretion, which causes vasodilation and decreases vascular resistance and mean arterial pressure, which increases the glomerular filtration rate during pregnancy.
Fluid retention in tissue �?carpal tunnel syndrome