Maternal Problems in Pregancy

Question 1

What does antenatal screening involve?

Answer 1

History & examination
- Risk factors - e.g. for gestational diabetes
Blood test
- Blood group
- Haemoglobin
- Infection
Urinalysis
- Protein

Question 2

How does the cardiovascular system change during pregnancy?

Answer 2

Cardiac output increases 40% from Term 1
Stroke volume increases 35% from T1
Heart rate increases 15% from T1
Systemic vascular resistance decreases 25-30% from T1

Blood pressure decrease in T1 & T2 but returns to normal in T3

Blood volume also increases.

Question 3

Tell me about the blood pressure changes during pregnancy.

Answer 3

Systolic BP is never increased in pregnancy (normally)

Hypotension

• T1 & T2 - progesterone effects on SVR
• T3 - aortocaval compression by gravid uterus

Question 4

How is the endothelium involved in pregnancy?

Answer 4

Controls vascular permeability
Contributes to the control of vascular tone
Vasodilation of pregnancy

Question 5

Compare pre-eclampsia to normal pregnancy in terms of cardiovascular system.

Answer 5

Normal
- Vasodilated
- Plasma-expanded
Pre-eclamptic pregnancy
- Vasoconstricted
- Plasma-contracted

Question 6

Outline the renal changes that occur during pregnancy.

Answer 6

Renal Plasma Flow increase 60-80%
Glomerular Filtration Rate increases by 55%
Creatinine clearance increases 40-50%
Protein excretion increases (up to 300mg/24hrs)
Urea decreases 50%
Uric acid decreases 33% (but rises with gestation)
Bicarbonate decreases (18-22mmol/L)
Creatinine decreases (25-75umol/L)

Filtration capacity intact
Functional renal reserve decreases as GFR increases

Question 7

What are the consequences of the renal changes seen during pregnancy?

Answer 7

Urinary stasis
- Progesterone effect on urinary collecting system
   - Hydroureter
- Obstruction
UTI
- Pyelonephritis
   - Pre-term labour

Question 8

Outline the changes in the respiratory system during pregnancy.

Answer 8

Anatomical changes
- Diaphragm displaced
- A-P and transverse diameters of thorax increase
Physiological changes

Question 9

What are the consequences of the respiratory changes seen during pregnancy?

Answer 9

Decreased functional residual capacity
Vital capacity unchanged, total lung capacity nearly unchanged
Increased minute & alveolar ventilation
Increased tidal volume, RR unchanged

So, physiological hyperventilation:
- Increased metabolic CO2 production
- Increased respiratory drive effect of progesterone
- Resulting in respiratory alkalosis, compensated by
increased renal bicarbonate excretion
“Physiological” dyspnoea
- Due to progesterone-driven hyperventilation

Question 10

How does carbohydrate metabolism change during pregnancy?

Answer 10

Placental transport of glucose via facilitated diffusion

So pregnancy increases maternal peripheral insulin resistance
- Switches to gluconeogenesis and alternative fuels

Achieved by:

• Human placental lactogen
  
  • Also, prolactin, oestrogen/progesterone and cortisol

Question 11

How does blood glucose change during pregnancy?

Answer 11

Decrease in fasting blood glucose

Increase in post-prandial (post-meal) blood glucose

Question 12

What is gestational diabetes?

Answer 12

A carbohydrate intolerance first recognised in pregnancy but does not persist after delivery

BUT there are risks associated with this poor control:

• Macrosomic fetus (large fetus - it’s own set of problems)
• Increased risk of stillbirth
• Increases rate of congenital defects

Oral glucose tolerance test is required

Question 13

What changes in lipid metabolism are there during pregnancy?

Answer 13

Increase in lipolysis from T2
Increase in plasma free fatty acids on fasting

(Free fatty acids provide substrate for maternal metabolism, leaving glucose for fetus)

Question 14

How does thyroid metabolism change during pregnancy?

Answer 14

Thyroid binding globulin production increased
T3 & T4 increased
Free T4 in normal range
hCG direct effect on thyroid stimulating thyroid hormone production
- TSH can be decreased in normal pregnancies.

Question 15

What are the anatomical changes in the gastrointestinal system during pregnancy?

Answer 15

Alterations in the disposition of viscera

- e.g. Appendix moves to RUQ as uterus enlarges

Question 16

What are the physiological changes in the gastrointestinal system during pregnancy?

Answer 16

Smooth muscle relaxation by progesterone
GI - delayed emptying
Biliary tract - stasis
Pancreas - increased risk of pancreatitis

Question 17

What is the significance of the haematology of a women during pregnancy?

Answer 17

Pregnancy is a pro-thrombotic state
Increase in fibrin deposition at the implantation site
Increased fibrinogen & clotting factors
Reduced fibrinolysis
Added to this - stasis; venodilation

Question 18

What are the consequences of the haematological changes during pregnancy?

Answer 18

Thromboembolic disease in pregnancy

BUT: warfarin crosses the placenta and is teratogenic!

Question 19

What is the link between pregnancy and anaemia?

Answer 19

During pregnancy:

• Plasma volume increases
• Red cell mass increases, but not by as much
• Physiological anaemia

However, anaemia due to Fe- and folate deficiency can occur
Also haemoglobinopathies

Question 20

What is the significance of the immune system during pregnancy?

Answer 20

Fetus is an allograft (a transplant?)
Non-specific suppression of the local immune response at the materno-fetal interface

Also transfer of antibodies:

• Haemolytic disease
• Graves disease and Hashimoto’s thyroiditis