physiological changes in pregnancy

Question 1

what are the maternal physiological changes of the GI system?

Answer 1

• reduced peristalsis (motility) of the GI tract
• increased absorption
• the smooth muscle of the oesophagus and the GI tract are relaxed due to effects of progesterone
• can be changes in taste preferences, food aversions or cravings or PICA
• constipation can occur due to decreased motility in the colon
• GI reflux (heart burn) is common due to reduced motility and relaxation of the oesophageal sphincter.

Question 2

What are the maternal physiological changes to cardiac output in pregnancy?

Answer 2

due to the increase in blood volume to facilitate the growth uterus and fetus and provide them with enough oxygen and nutrients, there is an increase in stroke volume (25-30%) as well as heart rate (10-15bpm) to facilitate this - which creates an increase in maternal cardiac output by 40-50% (heart rate + stroke volume).

The uterus in a non pregnant woman would take about 2% of the maternal blood circulation whereas a pregnant woman’s uterus will take up to 17% of the total maternal blood circulation by the 3rd trimester.

Question 3

What are the maternal physiological changes to the urinary system

Answer 3

1. due to the increased blood volume, the kidneys GFR increases by about 50%, however sometimes this means that some solutes can enter the urine (glucose and protein in trace amounts)
2. due to the effects of progesterone on smooth muscle, the urinary tract (bladder and ureters) become dilated which can cause urinary stasis.
3. Urinary stasis plus traces of glucose and protein in the urinary tract can create a susceptible area for bacterial growth making pregnant women more predisposed to UTIs than non pregnant women. The stasis of urine also makes it easier for bacteria to track up to the kidneys and cause pyelonephritis (renal infection), which can cause poor maternal and fetal outcomes. Thus it is important for UTIs to be identified and treated early.
4. the increase in blood volume means more urine is produced, therefore pregnant women may find the urge to micturate more frequently.

Question 4

What are the maternal physiological changes to the respiratory system

Answer 4

progesterone acts on the respiratory centre of the brain stimulating the the pregnant woman to breath more deeply - an increase of oxygen consumption of 16%, an increase in minute air flow by 50% .

The thoracic cavity reduces in volume due to the enlarged uterus pushing on the diaphragm causing an increase intrapulmonary pressure - however, the ribs tend to flare to widen the thoracic cavity and create more space