Physiology changes during pregnancy

Question 1

what causes morning sickness and in what conditions is it worse?

Answer 1

it isn’t clear what causes morning sickness but it is higher in conditions with increase HCG i.e molar pregnancy, twins

Question 2

what can morning sickness develop into if it becomes serious?

Answer 2

hyperemesis gravidarum

Question 3

in what trimester does the blood pressure drop?

Answer 3

second trimester

Question 4

how and why does heart rate change during pregnancy?

Answer 4

heart rate increases during pregnancy
CO has to increase therefore stroke volume and heart rate increase (CO = SV x HR)
this is to ensure there is enough blood flow to the uterus (> 1 litre)

Question 5

how does blood pressure change during pregnancy?

Answer 5

drops during second trimester:

• reduction in viscosity
• reduction sensitivity to angiotensin
• all in systemic vascular resistance

blood pressure usually returns to normal in third trimester

Question 6

what do you have to be wary of in the 3rd trimester with terms of blood pressure?

Answer 6

blood pressure normally rises during thirst trimester as it falls in the second trimester
but you have to be cautious as to whether this is returning to the pre pregnant blood pressure or if it is the start of pre eclampsia

Question 7

with regards to the urinary system, what happens to the levels of serum urea and creatinine?

Answer 7

both serum urea and creatinine decrease
this is because the plasma volume increases therefore dilutes the urea and creatinine concentration and also because GFR increases

Question 8

why are pregnant women prone to UTI’s and why can this become serious?

Answer 8

stasis of urine as the bladder doesn’t empty properly due to compression of the uterus
pyelonephritis is common in the 3rd trimester due to the UTI’s and this can cause pre term labour

Question 9

does haemoglobin increase or decrease during pregnancy and why?

Answer 9

haemoglobin decreases due to dilution

plasma volume increases by 50% and RBC mass increases by 25%

Question 10

by how much are iron requirements increased during pregnancy?

Answer 10

1g

Question 11

with regards to blood cells, do they increase or decrease…

1) RBC
2) WBC
3) platelet

Answer 11

RBC - decrease (by dilution)
WBC - increase
platelet count - decrease (by dilution)

Question 12

when should iron supplements be introduced?

Answer 12

when Hb < 110 or < 100 on routine testing after 28 weeks

Question 13

does respiratory rate increase or decrease during pregnancy and why?

Answer 13

progesterone acts centrally to decrease C02

therefore this increases tidal vol, resp rate and plasma PH

Question 14

what negative effect does increased respiratory rate due to decrease in C02 have?

Answer 14

due to increased 02 consumption (by 20%) because of increased tidal vol, respiratory rate and plasma PH, this causes hyperaemia of respiratory mucous membranes

Question 15

how does pregnancy cause heart burn?

Answer 15

oesophageal sphincter relaxes

pregnancy also slows down peristalsis and gastric emptying

Question 16

what is responsible for the decrease in gastric motility during pregnancy?

Answer 16

increase in progesterone

decrease in motillin

Question 17

what is responsible for thyrotoxicosis during pregnancy ?

Answer 17

HCG acts like TSH and binds to TSH receptors to cause the thyroid gland to produce more thyroxine

not antibodies mediated like Graves disease

Question 18

how is thyrotoxicosis treated in pregnancy?

Answer 18

symptomatically

not treated with thyroxine

Question 19

why does iodine requirements increase during pregnancy?

Answer 19

because of the increased thyroid hormone (thyroxine) produced due to HCG,

Question 20

what are the breast changes during pregnancy?

Answer 20

breast tissue increases in size and vascularity
warm tense and tender
increased pigmentation of aerial and nipple
secondary aerial appears
montgomery tubercles spear on areola
colostrum like fluid expressed after 3rd month

Question 21

why is there a reduction in the CO in a pregnant woman in the supine position?

Answer 21

the uterus compresses on the IVC therefore restricting blood flow back to the heart
if examining or in cardiac arrest etc lie patient at 45 degrees or at a left/right lateral tilt

Question 22

describe the changes in heart rate during and after labour.

Answer 22

during labour the heat rate increases due to auto transfusion of contractions
pain also increases the release of catecholamines which increases HR and BP

CO increases by 80% in 1st post delivery hour due to auto transfusion of a large amount of blood from contractions on an empty uterus

Question 23

what is the change in blood pressure post-partum?

Answer 23

BP initially falls bu then increases again 3-7 days and stabilises by 6 weeks

Question 24

what are the changes in PEFR and FEV1 during pregnancy?

Answer 24

unchanged

Question 25

does PC02 change during pregnancy?

Answer 25

decreases

Question 26

does urate increase or decrease during pregnancy?

Answer 26

decreases but increases with gestation

Question 27

what is urate (uric acid) often used to test in pregnancy?

Answer 27

pre eclampsia

Question 28

what is the upper level or normal urea and creatinine during pregnancy?

Answer 28

urea 4 (normal 7.1)
creatinine 60/70 (normal 60-110)

Question 29

does alkaline phosphate increase or decrease during pregnancy?
what could it be a marker of?

Answer 29

increases as it is released from the placenta

marker of obstetric cholestasis

Question 30

does d-dimer increase or decrease?

Answer 30

increases

Question 31

what is used to investigate DVT or PE in pregnancy? and why is d-dimer not used?

Answer 31

d-dimer is physiologically increased during pregnancy, so don’t know if it is pathologically increased

• risk stratification
• doppler (DVT)
• VQ scan (PE)

Question 32

what is the change in total protein and albumin in pregnancy?

Answer 32

decreases

Question 33

what is reponsible for insulin resistance during pregnancy?

Answer 33

placenta releases HCG antigen which causes insulin resistance

Question 34

what is used to test for gestational diabetes?

Answer 34

fasting glucose

HbA1c isn’t used as HbA1c decreases as pregnancy progresses therefore cannot use as a marker