Physiological Changes In Pregnacny Flashcards
What are the hormonal changes (in terms of oestrogen and progesterone) in pregnancy and what are they effects?
Progsterone increases:
- first 35 days produced by the corpus luteum and then production taken over by the placenta.
- results in reduced smooth muscle excitability of the ureters, uterus and bowel and increases body temperature.
Oestrogen increases:
- oestrogen is produced by the placenta
- causes enlargement of the breast and nipples, water retention and increased protein synthesis.
- the maternal thyroid often enlarges due to increased colloid production.
What are the thyroid hormone in pregnancy and what are their effects?
- increased oestrogen causes increased production of TBG
- this causes more TSH to be produced to increase the levels of free T3 and T4 back to normal
- hCG also mimics TSH which results in more production of T3 and T4
- this causes increased HR, warm skin, slight goitre and anxiety
Describe how the insulin-resistant state occurs in pregnancy and the effects.
Increase in human placental lactogen, prolactin and cortisol
These are anti-insulin hormones
They increase insulin-resistance in the mother and reduce peripheral uptake of glucose
The mother switches to lipid metabolism
This also, however, increases the risk of ketoacidosis
Describe the genital changes in pregnancy.
Uterine muscle hypertrophy until 20 weeks and then stretching.
May develop cervical ectropion.
Later on there is reduction of the cervical collagen
Increased vaginal discharge due to cell desquamation, increased mucus production from vasovaginal congestion and cervical ectropion
Describe the haematological changes in pregnancy.
Plasma volume increases during pregnancy, red cells don’t increase as much which can lead to dilutional anaemia.
Increased VTE risk
- increase in fibrinogen and clotting factors
- decrease in fibrinolysis
- increase in progesterone - stasis of blood and venodilation
Describe the cardiovascular system changes in pregnancy.
Due to progesterone decreasing peripheral vascular resistance there is a drop in BP especially diastolic.
Increase in cardiac output due to increased heart rate and increased stroke volume.
Increased venous pressure - may cause varicose veins.
Vasodilation and hypotension leads to RAAS activation
Describe aorto-caval compression in pregnancy.
From 20 weeks the gravid uterus compresses the inferior vena cava in the supine position reducing venous return which then reduces cardiac output by 30-40%.
It is important when examining a woman this far along to lie them in the left lateral position.
Describe the respiratory system changes in pregnancy.
Ventilation increases, with increased depth of breathing caused by progesterone
Hyperventilation due to increased CO2 resulting in respiratory alkalosis with a compensated increase in renal bicarbonate excretion.
Describe the GI system changes in pregnancy.
Increase in progesterone causes smooth muscle relaxation which decreases gut motility
This can lead to constipation and delayed gastric emptying.
It also causes relaxation of the lower oesophageal sphincter and in combination with the increased intra-gastric pressure due to compression can cause reflux and nausea.
Relaxation of the gallbladder can cause biliary tract stasis which then predisposes the mother to getting gallstones.
Describe the urinary system changes in pregnancy.
GFR increases by around 60%. This means there is increased renal excretion and lower levels of urea and creatinine. This causes increased frequency and then later so does compression of the bladder by the foetal head.
Women are more prone to UTIs and pyelonephritis due to relaxation of the smooth muscle of the bladder by progesterone resulting in stasis and relaxation of the ureters.
What are the dermatological changes in pregnancy?
Skin pigmentation (linea nigra, nipples, chloasma)
Palmar erythema, spider naevi
Striae
