Session 8: Maternal Physiological Adaptations in Pregnancy

Question 1

Give examples of broad physiological adaptations caused by pregnancy.

Answer 1

Metabolism

Glucose

Respiration

Kidneys

Cardiovascular

Haematological

GI

Endocrine

Question 2

What is the general driving force of the physiological maternal changes?

Answer 2

Hormones such as:

hCG

Oestrogen

Progesterone

hPL

Relaxin

Question 3

Why is fat laid down in first half of pregnancy?

Answer 3

To help meet the demands of the fetus later in the pregnancy.

Question 4

Explain the changes to fat, glucose and amino acids in pregnancy.

Answer 4

Blood glucose and amino acid conc. reduces.

Increased in maternal free fatty acids, ketone and triglyceride levels as an alternative metabolic fuel.

Question 5

Explain the insulin effect in pregnancy.

Answer 5

There is an increased insulin resistance in the second half of pregnancy as well as increased insulin release in response to a normal meal.

This is to allow increased glucose availability for the foetus.

Question 6

Function of hPL.

Answer 6

Generates maternal resistance to insulin.

Question 7

Give an example of a hormone that has a similar role to hPL.

Answer 7

Prolactin

Question 8

Function of oestrogen in materan adaptation.

Answer 8

Increase prolactin release

Question 9

Function of progesterone in maternal metabolism adaptations.

Answer 9

Increase appetite in first half of pregnancy and diverts glucose into fat synthesis.

Question 10

What is gestational diabetes?

Answer 10

Defined as glucose intolerance that is first recognised in pregnancy but does not persist after delivery.

Question 11

How to diagnose gestational diabetes.

Answer 11

Oral glucose tolerance test (OGTT) where resistance to insulin is not met with a compensatory rise in maternal insulin.

This leads to maternal hyperglycaemia.

Question 12

Complications of gestational diabetes.

Answer 12

Increased birth weight, congenital defects, stillbirth.

Question 13

What are the mother’s energy needs met by in later pregnancy?

Answer 13

Metabolising peripheral fatty acids.

Question 14

As the fetal-placental unit’s increasing need for nutrition progresses, how is this emt by cardiovascular changes?

Answer 14

Maternal vascular-neogenesis

Question 15

How else is the increasing need for nutrition of the foetus solved?

Answer 15

Increased blood flow by changes in function of the maternal baro and volume receptors.

Question 16

Where else is there increased blood flow in the mother?

Answer 16

To the growing breasts, kidneys and GI tract.

Question 17

How does plasma volume change in pregnancy?

Answer 17

Increased about 50%

Question 18

How does red cell mass change in pregnancy?

Answer 18

Increase about 20%

Question 19

How does CO change in pregnancy?

Answer 19

Cardiac output increases from about 4.5 to 6 litre/min.

Question 20

How is the increase in CO achieved?

Answer 20

Mainly by increased stroke volume

Question 21

Why might you hear flow murmurs in pregnancy?

Answer 21

Increased plasma volume

Question 22

Even though plasma volume increases as well as CO there is usually a fall in blood pressure in first and second trimester, to then go back to normal in third trimester.

How is this possible?

Answer 22

Because the high progesterone levels causes vasodilation. This leads to a fall in TPR and can result in hypotension.

Question 23

Explain the haematological changes in pregnancy.

Answer 23

Increase in clotting factors and fibrinogen and decrease in fibrinolysis. This leads to a pro-thrombotic state and can lead to thromboembolic disease in pregnancy.

The increase in blood volume is not proportional to the increase in red cell mass. The red cell mass doesn’t increase as much. This can lead to a physiological anaemia. Anaemia in pregnancy can also be caused by iron and folate deficiency.

Question 24

Why is not advised to treat thromboembolic disease in a pregnant woman with warfarin?

Answer 24

Because warfarin is a teratogen and can cause harm to the developing embryo/foetus.

Question 25

Explain the changes to respiratory function in pregnancy.

Answer 25

The baby needs O2 and so does the mother. Both also needs CO2 clearance. The RR (slight hyperventilation) is changed a little but tidal volume and O2 uptake increase significantly. This can lead to an awareness of the desire to breathe in pregnancy. This can be interpreted as dyspnoea (SOB)

Question 26

What is the increased respiratory effort and reduction in pCO2 caused by?

Answer 26

Progesterone acting directly on the resp centre and sensitising chemoreceptors to CO2 changes.

Question 27

Explain the change in renal functions in pregnancy.

Answer 27

Since there is increased renal blood flow there will also be increased GFR to 160% of normal.

Question 28

Since GFR is increased sodium excretion increases leading to potential hypotension. How is this compensated for?

Answer 28

Increased secretion of renin, aldosterone and angiotensin II. This leads to increase of creatinine clearance and serum levels of urea and creatinine fall. Also there can be some glucosuri as there may be decreased PCT absorption.

Question 29

Explain the GI changes in pregnancy.

Answer 29

Progesterone causes smooth muscle relaxation throughout the GI tract. This leads to slower gastric emptying. Decreased gallbladder contractility.

Question 30

Complications of GI tract changes.

Answer 30

Nausea Constipation Heartburn (GORD) Gallstones

Question 31

Explain the thyroid changes in pregnancy.

Answer 31

Thyroid changes where oestrogen causes TBG hepatic production. The increased TBG leads to increased thyroxine production. Since hCG has a similar alpha-subunit to TSH hCG also has a weak stimulating effect on the thyroid.

Question 32

Explain the PTH and calcium changes in pregancy.

Answer 32

Placenta can produce calcitriol. This increases maternal calcium absorption and greater calcium availability for the foetus to allow optimal bone development.

Question 33

MSK changes in pregnancy

Answer 33

Changes in center of gravity can lead to increased lordosis and kyphosis. Forward flexion of the neck. Increased mobility of sacroiliac joints and pubic symphysis.

Question 34

Complicaitons of MSK changes in pregnancy.

Answer 34

Back pain Shoulder pain Tension headaches Pelvic pain Carpal tunnel syndrome

Question 35

Skin changes in pregnancy.

Answer 35

Melasma Palmar erythema Vasicular piders Linea nigra Loose skin

Question 36

What is pre-eclampsia?

Answer 36

A condition relating to placental insufficiency.

Question 37

How does pre-eclampsia manifest itself?

Answer 37

By hypertension and proteinuria

Question 38

When does pre-eclampsia usually occur?

Answer 38

Third trimester.

Question 39

Risk factors of pre-eclampsia.

Answer 39

Chronic or gestational hypertension. Renal disease Diabetes Obesity FH Extremes of age IVF

Question 40

Pathogenesis of pre-eclampsia.

Answer 40

Impaired invasion of trophoblats leading to shallow invasion of spiral arteries. This leads to hypoperfusion and ischaemia. Placental insufficiency can also lead to low progesterone levels and therefore less vasodilation.

Question 41

Maternal complications of pre-eclampsia.

Answer 41

Can lead to eclampsia (seizures) Cerebral haemorrhage Renal failure Pulm oedema DIC and thrombocytopenia Hepatic failure

Question 42

Foetal complications of pre-eclampsia.

Answer 42

Growth restriction Oligohydramnios Placental infarct Fetal distress Premature delivery Stillbirth Miscarriage

Question 43

Treatment of pre-eclampsia

Answer 43

Stabilise BP Monitor blood results Monitor baby Fluid restriction

Question 44

What are the immunological changes in pregnancy?

Answer 44

Progesterone inhibits Th2 and Th1. This causes a immunosuppressed state important for the foetus. It can improve some autoimmune conditions but the mother becomes susceptible to viral pathogens like varicella zoster.

Question 45

Effect of angiotensin II in pregnancy.

Answer 45

No effect. Commonly thought to be due to the overriding effect of progesterone.

Question 46

Structural changes and its effects of the urinary tract in pregnancy.

Answer 46

Smooth muscle relaxation and obstruction leads to increased size of kidneys and ureters. This leads to decreased speed of urine passage.

Question 47

What does the diabetogenic state of pregnancy refer to?

Answer 47

Increased insulin resistance Increased insulin secretion

Question 48

Signs and symptoms of mild pre-eclampsia.

Answer 48

Hypertension Proteinuria Weight gain Oedema

Question 49

Signs and symptoms of severe pre-eclampsia.

Answer 49

Headaches Changes in vision Nausea Vomiting Abdominal and back pain