Maternal Physiological Adaptations To Pregnency Flashcards
What changes occur in the cardiovascular system?
- Increased blood volume
- Increased cardiac output
- Increased stroke volume
- Increased heart rate
Physiological changes occur to which maternal systems?
- CVS
- Urinary system
- Respiratory system
- GI system
- Immune system
- Metabolic system
What happens to BP in T1&2, and why?
Reduced blood pressure due to effects of progesterone systemic vascular resistance
Why does BP return to normal in T3?
Reduced return to heart due to aortocaval compression by gravid uterus
What changes occur in the urinary system?
- Increased renal plasma flow
- Increased GFR
- Urinary stasis
Why does urinary stasis occur?
Progesterone relaxes smooth muscles in the wall of the ureters
What are the consequences of urinary stasis?
- UTI
- Pyelonephritis
What is the danger of pyelonephritis in pregnancy?
Can induce pre-term labour
What anatomical changes occur in the respiratory system?
- Diaphragm is displaced
- A-P and transverse diameters of thorax increase
What physiological changes do/do not occur in the respiratory system?
- Increased Oxygen consumption
- Increased increased tidal volume
- Decreased functional residual capacity
- Vital capacity, FEV1 and Resp rate do not change
What drives physiological hyperventilation!
Progesterone
What does physiological hyperventilation result in?
Respiratory alkalosis with compensation
How does progesterone affect carbohydrate metabolism?
Stimulates maternal appetite in the first half of pregnancy and diverts glucose into fat synthesis
How does oestrogen affect carbohydrate metabolism?
Stimulates a rise in prolactin, leading to maternal insulin resistance
How do changes in carbohydrate metabolism benefit the fetus?
- Mother uses less glucose
- Gluconeogenesis increases
- This maximises glucose available to the fetus
What is gestational diabetes?
- Carbohydrate intolerance first recognised in pregnancy and not persisting after delivery
- Loss of control of metabolism leading to hyperglycaemia
Why does gestational diabetes occur?
- Endocrine pancreas is unable to respond to high metabolic demand of pregnancy
- Leading to a failure to release increased amount of insulin required
What changes occur in the thyroid?
- Increased thyroid binding globulin
- Increased T3 and T4
- Reduced TSH
What stimulates the thyroid gland in pregnancy?
hCG
Why can anaemia occur in pregnancy?
- Mismatch between plasma volume and haemocrit (physiological)
- Iron and folate deficiencies
Why does physiological anaemia occur?
- Plasma volume increases
- RBC mass does not increase to same degree
What anatomical changes occur in the GI system?
Appendix moves to LUQ as uterus enlarges
What physiological changes occur in the GI system and why?
- Delayed emptying
- Biliary tract stasis
- Due to relaxation of smooth muscle by progesterone
What changes occur to the immune system?
- Non-specific suppression of local immune response at materno-fetal interface as fetus is an allograft
- Haemolytic disease ➡️ ABO and rhesus antibodies do not cross the placenta
What are the features of a pre-eclamptic woman?
- Vasoconstricted
- Plasma-contracted
- Raised BP
- Proteinuria
- Pitting oedema
