Physiology of pregnancy

Question 1

Mechanical changes in pregnancy

Answer 1

pregnant person needs to lean backward and the curves of the spine change along its whole length. This is why pregnant people are more prone to back pain during (and after) pregnancy.

Question 2

Hormone produced in pregnancy?

- what effect does this have on

Answer 2

relaxin

• increased pliability and extensibility of connective tissue. Ligamentous joints become less stable.

Question 3

What joints are particularly affected In pregnancy?

Answer 3

symphysis pubis and sacroiliac joints

Question 4

the normal pubic symphyseal gap increases by?

Answer 4

4-5mm increase on average by another 3mm. (*symphysis pubis dysfunction).

Question 5

When does joint loosening occur

load on hip joints at term?

Answer 5

10 weeks and will return to normal 4-12 weeks post partum.

By term there is an increased load on the hip joints of 2.8 times the normal value when standing.

Question 6

what acts against maternal insulin

Answer 6

Human placental lactogen

Question 7

what are Fatty acids vital for

Answer 7

fetal organogenesis.

Question 8

normal female weight gain?

Answer 8

10-14 kg

Question 9

regarding eating food through pregnancy- what happens?

• what do hormones cause relaxation of? likely to cause?

Answer 9

food moves more slowly into the stomach and there is delayed emptying

• lower oesophageal sphincter - more likely for contents to reflux into oesophagus

Question 10

The mechanical pressure from an enlarging uterus makes makes what worse as does delayed gastric emptying?

Answer 10

mechanical pressure from an enlarging uterus

Question 11

what % of women will develop oedema?

Answer 11

80%

Question 12

why do women develop oedema in pregnancy?

Answer 12

physiological sodium and water retention and a decreased ability to excrete a sodium and water load

Question 13

increased BV in pregnancy leads to.. why is this?

Answer 13

decreased venous return due to compression of the inferior vena cava from the gravid uterus also contributes to peripheral oedema

Question 14

oedema can be an important sign of

Answer 14

pre eclampsia

Question 15

breast changes in pregnancy include?

Answer 15

pigmentation of the areola and nipple and a secondary areola appears

• Montgomery tubercles appear on the areola. Colostrum like fluid can be expressed from the end of the 3rd month.

Question 16

what does the liver produce more of in pregnancy?

do t3 and t4 change?

Answer 16

thyroid binding globulin (TBG) but the total level of thyroxine (T4) and tri iodothyronine (T3) also increase so FREE T3 and FREE T4 (active) levels remain the same.

Question 17

what is pregnancy associated with?

Answer 17

a relative iodine deficiency

Question 18

why do maternal iodine requirements increase in pregnancy?

• urinary exception and GFR?
• why does the thyroid gland work harder?

Answer 18

iodine is actively transported to the fetoplacental unit and urinary iodine excretion is doubled because of an increased glomerular filtration rate and decreased renal tubular reabsorption. The thyroid gland therefore works harder to increase its iodine uptake and may hyperthrophy to ensure adequate levels of iodine trapped.

Question 19

What can be associated with a biochemical hyperthyroidism (increased levels of T4 and suppressed TSH?

• why is this?

Answer 19

Hyperemesis gravidarum

• because the beta sub unit of BHCG (a pregnancy hormone) is structurally very similar to TSH.

Question 20

How is Hyperemesis gravidarum treated?

Answer 20

betablockers such as propanolol can be used for symptom control of tachycardia caused by the high levels of T4. This biochemical hyperthyroidism will resolve with the hyperemesis.

Question 21

what is overactive thyroid caused?

Answer 21

Thyrotoxicosis

Question 22

Thyrotoxicosis is often due to underlying?

Answer 22

Grave’s disease

Question 23

What can the antibodies that cause Graves disease do?

what are these antibodies called?

Answer 23

TSH receptor antibodies

• can cross the placenta and cause fetal and/or neonatal hyperthyroidism

Question 24

what is the foetus dependent on?

Answer 24

maternal thyroid functio

Question 25

when does fetal thyroid development begin?

Answer 25

12 weeks gestation.

Question 26

there Is a general state of immunosuppression in pregnancy - why is this? - what does this do?

Answer 26

to allow for fetal tolerance - increases the maternal susceptibility to infection

Question 27

What conditions can improve during pregnancy?

Answer 27

Crohns disease, rheumatoid arthritis

Question 28

the heart has to work harder due to? (4) | - what does it have too pump blood through?

Answer 28

- of the growing fetus, the weight gain associated with pregnancy and the increased oxygen requirements of the uterus and breasts

Question 29

previous or undiagnosed cardiac problems may show in pregnancy.. what my happen?

Answer 29

- may lead to maternal and fetal death | -

Question 30

What is the leading indirect cause of maternal death in the UK?

Answer 30

cardiac disease

Question 31

circulating blood volume in pregnancy increases by? relative haemodilution by red cell mass %?

Answer 31

50-70% - red cell mass also increases - 40%

Question 32

what causes the physiological anaemia of pregnancy?

Answer 32

red cell mass also increases by 40% - haemodilution

Question 33

the increase in circulating BV causes what to increase? - when will this be seen during gestation

Answer 33

the left ventricular end diastolic volume is increased and can be seen as early as 10 weeks on an echocardiogram (ECHO)

Question 34

the increased BV in pregnancy can cause problems for those with? (3)

Answer 34

dilated cardiomyopathy or lesions such as mitral stenosis or pulmonary hypertension.

Question 35

The resistance of all the peripheral vasculature in the systemic circulation (systemic vascular resistance) falls and is at its lowest at between?

Answer 35

20-32 weeks.

Question 36

(Systemic vascular resistance) equation?

Answer 36

``` SVR = Mean arterial pressure (MAP) – mean venous pressure (MVP) divided by Cardiac output (CO) ```

Question 37

who does the SVR drop?

Answer 37

because of increased circulating vasodilators and the diversion of blood into the low pressure uteroplacental unit.

Question 38

blood flow to kidneys increases by?

Answer 38

60-80%

Question 39

why is cardiac output increased in pregnancy?

Answer 39

the stroke volume – the amount of blood pumped out by the ventricle with each beat - is increased. The heart rate also increases.

Question 40

how do you calculate cardiac output?

Answer 40

stroke volume x heart rate

Question 41

cardiac output increases by? - who is at risk

Answer 41

30-50% by the end of the second trimester - aortic stenosis - those who can't increase CO

Question 42

By term, the heart rate of a pregnant person is usually ?

Answer 42

10-20 beats higher than their non-pregnant value

Question 43

what heart rhythm is not uncommon in pregnancy? - what conditions may cause this heart rhythm? (4)

Answer 43

sinus tachycardia - hypovolaemia, pulmonary embolus, sepsis should be considered depending on the clinical context.

Question 44

During pregnancy oxygen consumption can increase by ? | - what muscle is working harder

Answer 44

20-30% by term - myocardium

Question 45

for those who smoke older/obese/diabetic the risk of developing what condition during pregnancy is...?

Answer 45

those with CAD | - ischaemic heart disease and myocardial infarction

Question 46

why may a pregnant patient faint?

Answer 46

vena caval compression by the pregnant uterus, any pregnant patient lying supine will lose 25% of their cardiac output

Question 47

what to do in the event of a maternal collapse/cardiac arrest ??

Answer 47

MUST be resuscitated on a left lateral tilt or with the uterus manually displaced. YOU WILL NOT BE ABLE TO RESUSCITATE ANY PERSON WITH A GRAVID UTERUS WHO IS LYING FLAT BECAUSE OF THE REDUCTION IN CARDIAC OUTPUT THIS CAUSES. This is one of the reasons a perimortem CS/emptying of uterus is part of the pregnancy ALS algorithm.

Question 48

how much blood is added to circulation with each contraction?

Answer 48

500 mls

Question 49

why does pain increase Intrapartum?

Answer 49

increases circulating catecholamines and increases the heart rate, blood pressure and cardiac output (CO =SVxHR)

Question 50

how does CO vary during labour? - why does it vary?

Answer 50

during - increase of 10% after - 80% above already increased value - lack of uteroplacental unit to be supplied but also because of the immediate relief of inferior vena caval compression

Question 51

BP levels before and after birth

Answer 51

The blood pressure (BP) initially falls then increases again by 3-7 days after birth. The BP returns to prepregnancy levels by 6 weeks

Question 52

days after post delivery | does BV decrease?

Answer 52

3

Question 53

what % increase in minute ventilation RR can also be confused for?

Answer 53

40-50% - dyspnea

Question 54

because of relative hyperventilation, PCO2 levels are lower in pregnancy and the pregnant healthy person is in a state of ?

Answer 54

compensated respiratory alkalosis

Question 55

how does the enlarging uterus affect the diaphragm ?

Answer 55

by as much as 4cm and increases the diameter of the lower thorax by 2cm by splaying the lower ribs.

Question 56

what reduces by 20-30% in Resp changes?

Answer 56

Functional residual capacity

Question 57

asthma may improve in pregnancy due to?

Answer 57

the bronchodilator effect of progesterone.

Question 58

at 28 weeks- what is considered a normal Hg?

Answer 58

105 g/L or above is considered normal | - physiological anaemia

Question 59

non pregnant reference range of Hg?

Answer 59

120-160g

Question 60

what results due to the increase of plasma volume?

Answer 60

relative decrease in platelet count

Question 61

fold increase in iron for the fetus?

Answer 61

a 2-3 fold increase

Question 62

most common haematological abnormality of pregnancy?

Answer 62

Fe deficiency anaemi

Question 63

Going in to pregnancy with depleted Fe stores is common and may be due to? (3)

Answer 63

menorrhagia, inadequate diet, previous recent pregnancies

Question 64

Fe deficiency in pregnancy is also asoociated with?

Answer 64

intrauterine growth restriction

Question 65

folate increase is?

Answer 65

10-20 fold | - second most common cause of pregnancy anaemia

Question 66

WCC - normal value?

Answer 66

16x109/L is normal in pregnancy

Question 67

what clotting factors increase in pregnancy?

Answer 67

factors VII, IX and X increase as does fibrinogen

Question 68

What clotting factors decrease? | - what activity decreases?

Answer 68

Protein S and C and anti thrombin 3 levels decrease. | - Fibrinolytic activity decreases.

Question 69

why is t he risk of deep venous thrombosis in pregnancy increased? - the main causes of direct maternal mortality in the UK is?

Answer 69

venodilation and reduced venous return increasing venous stasis in the lower limbs. 6 times risk increase - Pulmonary embolus

Question 70

renal system - what it dilated? | what is it dilated?

Answer 70

of the urinary collecting system due to relaxation of the smooth muscle of the ureter caused by progesterone as well as the mechanical compression by the growing uterus.

Question 71

renal - what is more pronounced on the right.?

Answer 71

physiological hydronephrosi

Question 72

renal - what rates increase?

Answer 72

Glomerular filtration rate and creatinine clearance - 50%

Question 73

renal - the kidneys excrete more protein - what do they retain more of?

Answer 73

sodium ( and water).

Question 74

renal - Secretion of what is increased? (3)

Answer 74

vitamin D, renin and erythropoietin is increased.

Question 75

if there is no proteinuria, no infection and renal ultrasound and function is normal - what is more common? - why is this caused?

Answer 75

Microscopic haematuria - bleeding from the small vessels in the dilated renal function.

Question 76

renal - what is common

Answer 76

Glycosuria

Question 77

renal - infection common?

Answer 77

UTI - treat promptly with antibiotics known to be safe in pregnancy.