Maternal adaptations in pregnancy

Question 1

What producing oestrogen in pregnancy?

Answer 1

Placenta

Question 2

What produces progesterone in pregnancy?

Answer 2

Corpus luteum

Placenta

Question 3

How does oestrogen affect thyroid hormone levels?

Answer 3

Oestrogen causes an increase in hepatic production of thyroid binding globulin

More free T3 and T4 bind to TBG, this causes more TSH to be released from the anterior pituitary gland

Free T3 and T4 levels remain unchanged but the total T3 and T4 levels rise

Question 4

When does the foetal thyroid gland become functional

Answer 4

2nd trimester

Question 5

How does increasing T3 and T4 levels affect the foetus?

Answer 5

Ensures constant supply of thyroxin to the foetus in early pregnancy

Question 6

What is thyroxin essential for in the foetus?

Answer 6

Foetus neural development

Question 7

Name some anti-insulin hormones produced during 2nd trimester

Answer 7

Human placental lactogen
Cortisol
Prolactin

Question 8

Describe the action of anti-insulin hormones in pregnancy

Answer 8

Increase insulin resistance in the mother and reduce peripheral uptake of glucose
Ensures a continuous supply of glucose for the foetus

Question 9

Describe how there is a risk of ketoacidosis due to anti-insulin hormones in pregnancy

Answer 9

Mother switches to an alternative source of energy is provided by lipids

Increase in lipolysis means there is an increase in free fatty acids in the plasma

Breakdown of lipids can result in ketogenesis

Question 10

Describe how progesterone affects the cardiovascular system

Answer 10

Decreases systemic vascular resistance

Decreases diastolic blood pressure during 1st and 2nd trimester

Cardiac output increases by 30-50%

Activation of renin-angiotensin-aldosterone system, leading to an increase in sodium levels and water retention - total blood volume increases

Question 11

Describe how the growth of the foetus affects the woman’s respiratory system

Answer 11

Causes upward displacement of the diaphragm

Increase in transverse and anterior posterior diameters of the thorax

So total lung capacity not significantly changed

Question 12

What happens to the metabolic rate in pregnancy

Answer 12

Increases

Question 13

What does the increased metabolic rate in pregnancy cause

Answer 13

Increased demand for oxygen

Tidal volume and minute ventilation rate increases to help mother meet these oxygen demands

Question 14

Describe why many women experience hyperventilation during pregnancy

Answer 14

Increased carbon dioxide production and the increased respiratory drive caused by progesterone

Hyperventilation results in respiratory alkalosis with a compensated increase in renal bicarbonate excretion

Question 15

Describe the gastrointestinal anatomical changes caused by pregnancy

Answer 15

Upward displacement of the stomach - Increase in intra-gastric pressure - GORD

Appendix moves to right upper quadrant

Question 16

What happens to gut motility in pregnancy

Answer 16

Smooth muscle relaxation and gut motility decreased

May predispose to gallstones

Question 17

How much does GFR increase by with pregnancy

Answer 17

Increases by 50-60%

Question 18

What happens to the levels of urea and creatinine in pregnancy

Answer 18

Lower

Question 19

What does progesterone do to the urinary collecting system

Answer 19

Relaxation of the muscles of ureter and bladder

Predisposes to UTIs

Question 20

What happens to fibringoen and clotting factors in pregnancy

Answer 20

Increase

Question 21

What happens to fibrinolysis in pregnancy

Answer 21

Decreases

Question 22

What are pregnant people more likely to experience in terms of haematology

Answer 22

VTE

Dilatational anaemia

Question 23

Describe the formation of dilutional anaemia in pregnancy

Answer 23

Increased plasma volume

Red cell mass stays the same