Session 8: Maternal Physiological Adaptations in Pregnancy Flashcards
Give examples of broad physiological adaptations caused by pregnancy.
Metabolism
Glucose
Respiration
Kidneys
Cardiovascular
Haematological
GI
Endocrine
What is the general driving force of the physiological maternal changes?
Hormones such as:
hCG
Oestrogen
Progesterone
hPL
Relaxin
Why is fat laid down in first half of pregnancy?
To help meet the demands of the fetus later in the pregnancy.
Explain the changes to fat, glucose and amino acids in pregnancy.
Blood glucose and amino acid conc. reduces.
Increased in maternal free fatty acids, ketone and triglyceride levels as an alternative metabolic fuel.
Explain the insulin effect in pregnancy.
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.
Function of hPL.
Generates maternal resistance to insulin.
Give an example of a hormone that has a similar role to hPL.
Prolactin
Function of oestrogen in materan adaptation.
Increase prolactin release
Function of progesterone in maternal metabolism adaptations.
Increase appetite in first half of pregnancy and diverts glucose into fat synthesis.
What is gestational diabetes?
Defined as glucose intolerance that is first recognised in pregnancy but does not persist after delivery.
How to diagnose gestational diabetes.
Oral glucose tolerance test (OGTT) where resistance to insulin is not met with a compensatory rise in maternal insulin.
This leads to maternal hyperglycaemia.
Complications of gestational diabetes.
Increased birth weight, congenital defects, stillbirth.
What are the mother’s energy needs met by in later pregnancy?
Metabolising peripheral fatty acids.
As the fetal-placental unit’s increasing need for nutrition progresses, how is this emt by cardiovascular changes?
Maternal vascular-neogenesis
How else is the increasing need for nutrition of the foetus solved?
Increased blood flow by changes in function of the maternal baro and volume receptors.
Where else is there increased blood flow in the mother?
To the growing breasts, kidneys and GI tract.
How does plasma volume change in pregnancy?
Increased about 50%
How does red cell mass change in pregnancy?
Increase about 20%
How does CO change in pregnancy?
Cardiac output increases from about 4.5 to 6 litre/min.
How is the increase in CO achieved?
Mainly by increased stroke volume
Why might you hear flow murmurs in pregnancy?
Increased plasma volume
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?
Because the high progesterone levels causes vasodilation. This leads to a fall in TPR and can result in hypotension.
Explain the haematological changes in pregnancy.
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.
Why is not advised to treat thromboembolic disease in a pregnant woman with warfarin?
Because warfarin is a teratogen and can cause harm to the developing embryo/foetus.
Explain the changes to respiratory function in pregnancy.
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)
What is the increased respiratory effort and reduction in pCO2 caused by?
Progesterone acting directly on the resp centre and sensitising chemoreceptors to CO2 changes.
Explain the change in renal functions in pregnancy.
Since there is increased renal blood flow there will also be increased GFR to 160% of normal.
Since GFR is increased sodium excretion increases leading to potential hypotension. How is this compensated for?
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.
Explain the GI changes in pregnancy.
Progesterone causes smooth muscle relaxation throughout the GI tract.
This leads to slower gastric emptying.
Decreased gallbladder contractility.
Complications of GI tract changes.
Nausea
Constipation
Heartburn (GORD)
Gallstones
Explain the thyroid changes in pregnancy.
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.
Explain the PTH and calcium changes in pregancy.
Placenta can produce calcitriol.
This increases maternal calcium absorption and greater calcium availability for the foetus to allow optimal bone development.
MSK changes in pregnancy
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.
Complicaitons of MSK changes in pregnancy.
Back pain
Shoulder pain
Tension headaches
Pelvic pain
Carpal tunnel syndrome
Skin changes in pregnancy.
Melasma
Palmar erythema
Vasicular piders
Linea nigra
Loose skin
What is pre-eclampsia?
A condition relating to placental insufficiency.
How does pre-eclampsia manifest itself?
By hypertension and proteinuria
When does pre-eclampsia usually occur?
Third trimester.
Risk factors of pre-eclampsia.
Chronic or gestational hypertension.
Renal disease
Diabetes
Obesity
FH
Extremes of age
IVF
Pathogenesis of pre-eclampsia.
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.
Maternal complications of pre-eclampsia.
Can lead to eclampsia (seizures)
Cerebral haemorrhage
Renal failure
Pulm oedema
DIC and thrombocytopenia
Hepatic failure
Foetal complications of pre-eclampsia.
Growth restriction
Oligohydramnios
Placental infarct
Fetal distress
Premature delivery
Stillbirth
Miscarriage
Treatment of pre-eclampsia
Stabilise BP
Monitor blood results
Monitor baby
Fluid restriction
What are the immunological changes in pregnancy?
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.
Effect of angiotensin II in pregnancy.
No effect.
Commonly thought to be due to the overriding effect of progesterone.
Structural changes and its effects of the urinary tract in pregnancy.
Smooth muscle relaxation and obstruction leads to increased size of kidneys and ureters. This leads to decreased speed of urine passage.
What does the diabetogenic state of pregnancy refer to?
Increased insulin resistance
Increased insulin secretion
Signs and symptoms of mild pre-eclampsia.
Hypertension
Proteinuria
Weight gain
Oedema
Signs and symptoms of severe pre-eclampsia.
Headaches
Changes in vision
Nausea
Vomiting
Abdominal and back pain
