Table 1.

Physiological changes during pregnancy.

Cardiovascular system	Decrease peripheral vascular resistance Increased heart rate Decreased arterial pressure Increased cardiac output Increase in total body water, capillary hydrostatic pressure, and blood volume	(Sanghavi and Rutherford, 2014; Furfaro et al., 2018)
Respiratory system	Mucosal changes in the upper airway include edema, hyperemia, leakage of plasma into the stroma, glandular hypersecretion, increased mucopolysaccharide content and increased phagocytic activity Increased tidal volume Decreased residual volume Increased minute-ventilation by 30-40% increased respiratory center simulation → increased respiratory rate Decreased PaCO2	(Hegewald and Crapo, 2011; Cordioli et al., 2013)
Gastrointestinal system	Decreased muscle tone across the digestive tract Delayed gastric emptying and diaphragm elevation by the pregnant womb Increase in gastric PH and reduced gastrointestinal motility Increased production of pro-inflammatory cytokines by Kupffer cells Changes in bile composition	(Cordioli et al., 2013; Furfaro et al., 2018; Gomes et al., 2018)
Renal system	The glomerular filtration rate increases by 50% Decrease in serum urea, creatinine, and uric acid values Ureteropelvic dilation and decreased ureteral pressure due to smooth muscle relaxation Increased intravesical pressure due to the pregnant uterus weight Increased renal plasma flow and vesicoureteral reflux Asymptomatic bacteriuria Flaccid bladder	(Cordioli et al., 2013; Cheung and Lafayette, 2013)
Genital system	Decreased vaginal Ph Increased glycogen in vaginal epithelium Increased uterine blood flow and the vascular bed proliferates Uterus increases in size to contain the growing fetus	(Parry and Vodstrcil, 2007; Cordioli et al., 2013)
Hematologic system	Increases factors VII, VIII, IX, X, XII, Von Willebrand and fibrinogen Decreased fibrinolytic activity Decreased protein S Increased plasma and red cell volume Anemia	(Cordioli et al., 2013)