15 - Maternal Physiology Flashcards
In general, what are the physiological adaptations that occur in pregnancy?
When are hCG at their highest?
- Highest 8-12 weeks then fall as placenta takes over steroid production from corpus luteum
What are the immunological changes that occur in pregnancy?
- Mother is immunocompromised so doesn’t attack fetus
- Conditions like psoriasis can improve whilst pregnant
What are some respiratory changes that occur in a pregnant woman?
- Needs to increase CO2 clearance and O2 delivery
- Increase resp rate a little
- Tidal volume increased which can feel like dypsonea
- Increased respiratory effort and reduction in pCO2 is due to progesterone sensistising chemoreceptors to CO2
Why do most pregnant women feel dysponea?
Progesterone induced hyperventilation and low pCO<em><strong>2</strong></em>, also need to think about pathological factors like PE, asthma, pneumonia, anaemia, pulmonary oedema
What are some of the cardiovascular changes in a pregnant woman?
- Increased SV and HR
- Increased blood flow to breasts, kidney’s and GI
- Decreased SVR as progesterone causes vasodilation of vessels
How does a pregnant woman increase their SV and why may they be hypotensive even though they have more volume?
- Hypotensive as progesterone causes vasodilation and decreased SVR
- Cardiac output goes from 4.5L to 6L
What are some potential consequences of changes to the cardiovascular system in a pregnant woman?
- Peripheral oedema
- Dilution anaemia (can also be due to folate and iron deficiency)
- Flow murmur
- Upward displacement of apex beat
- Hypotension (usually returns to normal by 3rd trimester)
Why are pregnant women in a hypercoagulable state?
- Decreased fibrinolysis
- Increased clotting factors and fibrinogen
- Decreased anticoagulants
- Compression of vena cava
Can’t take warfarin as tetatrogenic so at risk of DVTs, PEs, haemorrhoids, varices
What are some changes to renal function that occur in pregnancy and what consequences can they cause?
- Increased RBF so increased GFR by 160%
- Increased RAAS compensate for expected sodium loss
- Serum levels of urea and creatinine fall
What are some GI changes that occur in pregnancy, and what consequences can they cause?
- Progesterone causes smooth muscle relaxation to slow emptying so more absorption of nutrients
Heart burn, constipation, gall stones
How may the presentation of appendicitis in a pregnant woman be different to the classical presentation?
Uterus may displace the bowel upwards so pain higher up
What are some changes to thyroid function in pregnancy?
Vital for fetal development so fetus takes the mothers levothyroxine so mother has to produce more TSH to make more T3/T4
What changes to calcium metabolism during pregnancy?
- PTH levels rise
- Placenta makes more hydroxylase so more calcitriol to increase mother’s Ca absorbption so more Ca for fetal bone growth
What are some changes to glucose metabolism in a pregnant woman?
- Reduction in maternal blood glucose and aa’s
- Diminished maternal responsiveness to insulin in second half of pregnancy
- Increased insulin release after normal meal
- Increase in maternal free fatty acid, ketone and TAG levels as an alternative fuel
How do changes in glucose metabolism occur, in terms of the hormones involved?
- hPL (a.ka hPS): generates maternal resistance to insulin. prolactin does this too
- Oestrogen: stimulates prolactin release
- Progesterone: increases appetite and diverts glucose into fat synthesis
How are mother’s energy needs met in pregnancy?
- Glucose used declines as insulin resistance
- Gluconeogenesis and peripheral fatty acids supply mother with energy so fetus can have glucose
What is gestational diabetes mellitus?
- Glucose intolerance first recognised in pregnancy and does not persist after delivery.
- Risk of developing Type II DM later in life.
- Diagnosed with OGTT
- Resistance to insulin not met with compensatory rise in insulin so mum is hyperglycaemic
What are the risks with gestational DM?
- Macrosomic baby as more insulin in baby that acts like growth factor
- Congenital defects
- Still birth
What are some changes that occur to the musculoskeletal system in pregnancy?
What are some skin changes that occur in pregnancy?
Increased MSH
What is preeclampsia?
Condition relating to placental insufficiency where there is hypertension and proteinuria
- Impaired invasion of trophoblast leads to shallow invasion of spiral arteries so high resistance. Hypoperfusion and ischemia
What are some risk factors of pre-eclampsia?
What are some of the complications of pre-eclampsia?
