T2 L18 Physiology of pregnancy

Question 1

Why is there an increase in physiological demands for the foetus and placenta?

Answer 1

Nutrients - O2, amino acids, glucose
Amniotic fluid production
Removal of foetal waste products

Question 2

How much does plasma volume increase in pregnancy?

Answer 2

40%
2.5 to 3.7L
8-10kg of fluid weight gain

Question 3

What is the consequence of the fall in plasma colloid osmotic pressure?

Answer 3

Causes shift of fluid into extracellular space
Increased hydration of connective tissue
Oedema in lower limbs, hands and face

Question 4

Describe the mechanism for an increase in plasma volume

Answer 4

Slight decrease in atrial natriuretic peptide
Decreased thirst threshold
Re-setting osmostat

Question 5

What is the function of the renin angiotensin system in the placenta?

Answer 5

Responsible for local regulation of trophoblast invasion and uterine / placental blood flows

Question 6

How much does red cell mass increase?

Answer 6

Increased by 25%

Question 7

How is iron increased to meet the needs of the increased red cell mass?

Answer 7

Fall in ferritin levels

Increased iron absorption from the gut

Question 8

How is blood delivered to the uterus?

Answer 8

Uterine artery

Question 9

How much does uterine artery flow increase?

Answer 9

From 95 to 342ml/min

Question 10

How much blood is lost at placental separation?

Answer 10

500ml/min

Question 11

Describe the change in white blood cells during pregnancy

Answer 11

Concentration doesn’t fall during pregnancy
Total WBC increases in pregnancy
Marked increase around delivery

Question 12

What does an increased blood volume have an impact on?

Answer 12

Cardiac output
Peripheral resistance
Blood pressure

Question 13

Why is there an increase in CO?

Answer 13

Increase in stroke volume and heart rate

Question 14

Why does peripheral resistance decrease?

Answer 14

Progesterone causes peripheral vasodilation

Question 15

How much does the heart enlarge during pregnancy?

Answer 15

12%

Question 16

Why does the heart enlarge?

Answer 16

There is increased venous return

Question 17

How common are systolic murmurs in pregnancy?

Answer 17

Common - 90%

Question 18

Why can you get an innocent diastolic murmur?

Answer 18

Reflects increased flow across atrioventricular valves

Question 19

How much does the kidney increase in size during pregnancy?

Answer 19

1cm

Question 20

How much do GFR and effective renal plasma flow increase during pregnancy?

Answer 20

≥50%

Question 21

Why do you get glycosuria in pregnancy?

Answer 21

There is a decrease in glucose reabsorption

Question 22

Why does the risk of a UTI increase during pregnancy?

Answer 22

Progesterone causes dilation of renal pelvis and ureter

Question 23

Why does gastro-oesophageal reflux increase during pregnancy?

Answer 23

Increased abdominal pressure

Reduced pyloric sphincter with backwash of bile

Question 24

How can gastro-oesophageal reflux be reduced?

Answer 24

Avoidance of fat and alcohol
Upright posture
Antacids

Question 25

What is the effect of progesterone on the gut?

Answer 25

Slowing of gut motility and constipation

Question 26

Describe glucose metabolism in the first trimester

Answer 26

Increased sensitivity to insulin

Increased glycogen synthesis and fat deposition

Question 27

Describe glucose metabolism in the second trimester

Answer 27

Insulin resistance
Cortisol, progesterone, HPL and oestrogen are all insulin antagonists
Glucose levels may rise and there are an increase in fatty acids

Question 28

What is the role of folate?

Answer 28

DNA synthesis, repair and regulation

RBC development

Question 29

What is the change in folate requirement during pregnancy?

Answer 29

50mg to 400mg

Question 30

How does thyroid function change during pregnancy?

Answer 30

Increased iodine absorption
Increased serum T3 and T4 levels
Increase in thyroid binding globulin due to oestrogen

Question 31

What hormones are produced by the placenta?

Answer 31

hCG (human chorionic gonadotrophin)
hPL (human placental lactogen)
hPG (human placental gonadotrophin)
CRH
Progesterone
Oestrogen

Question 32

When is hCG first detectable?

Answer 32

8-9 days after ovulation

Question 33

When does hCG peak?

Answer 33

8-10 weeks

Question 34

When is hCG significantly lower?

Answer 34

Ectopic pregnancy

Risk of miscarriage

Question 35

What is the alpha subunit of hCG similar to?

Answer 35

LH
FSH
TSH

Question 36

What is the role of hCG?

Answer 36

Maintains corpus luteum secretion of progesterone and oestrogen
Decreases as placental production of progesterone increases
May have a role in maternal oestrogen secretion and modulation of maternal immune response later in pregnancy

Question 37

What does hPL have a similar structure to?

Answer 37

Prolactin and growth hormone

Question 38

What does hPL do?

Answer 38

Alters maternal carbohydrate and lipid metabolism to provide for foetal requirements

• mobilise maternal free fatty acids
• inhibit maternal peripheral uptake of glucose
• increase insulin release from pancreas

Question 39

What is placental growth hormone responsible for?

Answer 39

Regulating foetal growth

Induces maternal insulin resistance

Question 40

What does placental corticotrophin releasing hormone do?

Answer 40

Stimulates production of maternal ACTH and cortisol

Question 41

Describe the effects of high levels of cortisol on the foetus

Answer 41

High levels early on are linked to slower rate of cognitive development post-partum
High levels later on are linked to accelerated cognitive development postpartum

Question 42

What does progesterone do?

Answer 42

Maintains uterine quiescence by decreasing uterine electrical activity
Immune suppressor
Lobulo-alveolar development in breasts
Substrate for foetal adrenal corticosteroid synthesis

Question 43

What is the effect of oestrogen?

Answer 43

Growth of uterus, cervical changes
Development of ductal system of breasts
Stimulation of prolactin synthesis
Stimulation of CBG, SHBG, TBG