Physiology in Pregnancy Flashcards
What mechanical changes occur to the mother’s body during pregnancy?
Relaxin (a hormone produced by the placenta) relaxes joints incl the pubic symphysis –> the pelvis more roomy in prep for birth/growth of baby
What changes occur to the pregnant mother’s metabolism?
Become easily fatigued
Why are pregnant woman more likely to get heart burn/reflux?
Hormones relax LOS
Physical presence of baby putting pressure on stomach/oesophagus
Under GA, what are pregnant woman more at risk of?
Aspiration
What is the presence of oedema associated with in pregnancy?
Pre-eclampsia
Also uterus presses on pelvic veins –> back up of blood –> lower leg/ankle oedema/varicose veins
Does thyroxine decrease or increase in pregnancy?
Increases to meet higher metabolic demand
Why might you get goitre in pregnancy?
Increased iodine loss due to iodine being sent to the foetus –> iodine deficiency which the thyroid can compensate for –> goitre
Why is there a general state of immunosuppression in pregnancy?
Baby is like a parasite, must go into this state so mother doesn’t reject foetus
What is normal wt gain in pregnancy?
2kg in 1st & 5kg in 2/3rd trimester is normal
More if twins, oedema etc
How do the breasts change in pregnancy?
Inc. in size and vascularity - become warm, tense & tender
Oestrogen/progesterone –> ant. pituitary to release prolactin –> milk production
Pigmentation of areola/nipple
Secondary areola appears
Montgomery tubercles appear on areola
Colostrum like fluid can be expressed by end of 3rd month
Why do the nipples darken in pregnancy?
Ant. pituitary releases more melanocyte stimulating hormone –> this darkens the nipples and can also darken the linea alba –> linea gravidarum/nigra
What are montgommery tubercles?
Small bumps that produce oil to lubricate the areola and nipple during pregnancy/lactation
What is colostrum?
Thick, sticky fluid that is perfect neonate food
When do the significant changes to the CV system occur in pregnancy?
1st trimester
What changes occur to the circulating volume & red cell count?
Circulating BV increases by 50-70%
RCC only increases a little
Therefore physiological anaemia results
What other changes occur to the CV system during pregnancy?
Systemic vascular resistance falls (20-32wks) --> drop in TVPR --> pink, warm skin, prone to nosebleeds Increased BF Increased CO & therefore SV Increased HR (10-20bmp) Increased O2 consumption Lower BP at start/middle of pregnancy BP rises after 32 weeks
Why is BP lower at start/middle of pregnancy?
Progesterone causes the BVs to dilate
Why must you never examine a pregnant lady supinely?
25% reduction in CO due to compression of IVC by foetus
Why must you never try to resus a pregnant woman supinely?
Most likely to be unsuccessful - use left lateral/manually displace the foetus
What are the intrapartum CV changes?
Autotransfusion of contraction - 1 contraction pushes 500ml blood to heart
Pain due to inc. catecholamines increases HR and BP
CO increases by 10% in labour & 80% in 1st post delivery hour
What do you need to be careful of in woman giving birth who have CAD?
Extra strain on the heart increases risk of IHD
Give epidural to reduce pain and catecholamines –> therefore reducing peripheral vasodilation
When does the CV system return to normal after pregnancy?
3 months
What respiratory changes occur during pregnancy?
Inc. in oxygen demand - lungs squashed but must work harder 50% increase in minute ventilation Increase in RR, TV & reduced FRC PEFR & FEV1 unchanged Decrease in PCO2
Why are asthmatics usually better during pregnancy?
Progesterone is a bronchodilator
What % of woman experience SoB during pregnancy?
33%
How do the structure of the kidneys change during pregnancy?
Compensate for extra workload by increasing in size –> dramatic dilatation of calyces & renal pelvis –> physiological hydronephrosis (& hydroureter)
More pronounced on R side (as uterus tilts to R)
How does GFR change in pregnancy?
Renal plasma flow increases by 60-80% so GFR and creatinine clearance increase by 50%
What % of pregnant woman develop oedema?
80%
There is extra protein excretion
What dipstick finding is common in pregnancy and not indicative of disease?
Glycosuria
In relation to renal function:
______ increases with gestation, _______ & ________decrease
Urate increases
Urea and creatinine decrease
Why are pregnant woman more prone to UTIs?
More bladder stasis (progesterone leads to hypomotility of the ureters & ureters shorter)
Why is their increased urinary frequency in pregnancy?
Increased GFR & pressure on bladder
Why is their relative insulin resistance in pregnancy?
Placenta produces human placental lactogen which counters the effect of maternal insulin to make sure there is plenty glucose for the foetus
How can you work out an expected uric acid level in a pregnant woman?
Relates to no of weeks gestation
e.g. 20 weeks, expect 200
What is high uric acid a marker of?
Pre-eclampsia
But not diagnostic
Also higher in twins/obesity
What are the haematological changes that occur during pregnancy?
Plasma vol increases Decrease in Hb, hcrit, RCC, platelet count No change in MCV, MHCH WCC increase 2-3x increase for iron Hypercoagulable state (for child birth) 10-20x increase in folate req.
How do CRP and ESR change during pregnancy?
CRP tends to stay the same - helpful marker of inflammation
ESR goes up - DONT USE IN PREGNANCY
How does albumin change during pregnancy?
Goes down - contributes to oedema
How does AST/ALT/GGT/Alk phos change in pregnancy?
Alk phos increases (placenta produces it)
AST/ALT/GGT may go down or stay the same
How does D-dimer change in pregnancy?
Goes up
Can’t use it to help diagnose DVTs/PEs
