Physiology of pregnancy

Question 1

What does a fertilized ovum develop into?

Answer 1

Blastocyst

Question 2

What do the inner & outer cells of a blastocyst develop into?

Answer 2

Inner cells = embryo

Outer cells = placenta

Question 3

When are the placenta & foetal heart functional by?

Answer 3

Week 5

Question 4

What is the purpose of the placenta villi?

Answer 4

AV shunt - stops direct contact of mother & child blood

Nutrient transfer

Question 5

How does foetal oxygenated blood return to the foetus?

Answer 5

Umbilcal vein

Question 6

How does a foetus maintain a good oxygen supply?

Answer 6

Foetal Hb has increased ability to carry oxygen
High Hb conc in foetal blood
Bohr effect (foetal Hb can carry more oxygen in low PCO2 then high pCO2)

Question 7

What is the function of hCG in pregnancy?

Answer 7

Prevents corpus luteum from forming

Effects development od sex organs

Question 8

What are the effects of HCSinpregnancy?

Answer 8

Growth effects
Decreases insulin sensitivity in mother
Involved in breast development

Question 9

What are the effects of progesterone in pregnancy?

Answer 9

Develop decidual cells
Decreases uteruscontractility
Prep for lactation

Question 10

What are the effects of oestrogen in pregnancy?

Answer 10

Enlarges uterus
Breast developemnt
Relax ligaments

Question 11

How does CRH secreted by the placenta affect the mother?

Answer 11

Causes increased ACTH which causes increased aldosterone & cortisol
This can lead to hypertension or oedema causing insulin resistance and gestational diabetes

Question 12

What condition can HCG secreted by the placenta cause in the mother?

Answer 12

Hyperthyroidism

Question 13

What condition can increased calcium demands from the plaenta cause in the other?

Answer 13

Hyperparathyroidism

Question 14

How does pregnancy affect maternal cardiac output?

Answer 14

Increase (by 30-50%) then decreases in the last 8 weeks

Question 15

How does pregnancy affect the maternal HR?

Answer 15

Increase (up to 90bpm)

Question 16

Why does maternal blood pressure drop in the second trimester of pregnancy?

Answer 16

Circulation expands

Peripheral resistance decreases

Question 17

What maternal haematological changes are seen in pregnancy?

Answer 17

PV increases (proportional with CO)
Erythropoesis increases
Decreased Hb by dilution
Iron requirement increases

Question 18

What effect does progesterone have on CO2 levels?

Answer 18

Progesterone signals to brain to lower CO2 levels

Question 19

What affect does pregnancy have on the kidneys?

Answer 19

Decreased GFR & renal plasma flow
Increased reabsorption of ions & water
Slight increase in urine formation

Question 20

What is pre-eclampsia?

Answer 20

Pregnancy induced hypertension + proteinuria (<0.3g/24hrs)

Question 21

What are the risk factors for pre-eclampsia?

Answer 21

Previous pre-eclampsia 
Hypertension 
Diabetes 
Renal disease
Obesity 
Twins

Question 22

When is pre-eclampsia seen?

Answer 22

After 20 weeks

Question 23

Symptoms of pre-eclampsia

Answer 23

Headache 
Visual disturbances 
Papilloedema 
RUQ/epigastric pain 
Hyperreflexia

Question 24

What is the first line treatment for pre-eclampsia in pregnancy?

Answer 24

Labetalol

Question 25

How is gestational hypertension defined?

Answer 25

>20 weeks No proteinuria, no oedema Resolves following birth BP > 140/90

Question 26

What is used to prevent & treat seizures in eclampsia?

Answer 26

IV Magnesium sulphate 4mg blous followed by infusion of 1g/hour

Question 27

What are 2 phases of pregnancy metabolism?

Answer 27

<20 weeks = mothers anabolic phase | >20 weeks = increased foetal demand/starvation of the mother

Question 28

How do progesterone & oestrogen affect contractility of the uterus?

Answer 28

Progesterone inhibits contractility | Oestrogen increases contractility

Question 29

What is the role of oxytocin in labour?

Answer 29

Increases contractions & excitability

Question 30

What controls the timing of labour?

Answer 30

Foetal hormones (oxytocin, adrenal gland, prostaglandin)

Question 31

What are the 3 stages of labour?

Answer 31

1st stage = cervical dilation (8-24 hours) 2nd stage = passage through birth canal (few min-30 min) 3rd stage = expulsion of placenta

Question 32

How does oestrogen affect the breasts?

Answer 32

Stimulates growth of ductile system | Inhibits milk production

Question 33

How does progesterone affect the breast?

Answer 33

Development of lobule-alveolar system | Inhibits milk production

Question 34

What change in hormones brings about milk production?

Answer 34

Drop in oestrogen & progesterone (both inhibit milk production) Increased prolactin & oxytocin

Question 35

What re the changes inprolactin in pregnancy?

Answer 35

Increases week 5 to birth | Stimulates colostrum

Question 36

What causes the milk "let-down" reflex?

Answer 36

Sucking stimulus + oxytocin