6. Pregnancy related conditions

Question 1

why can smoking result in premature delivery, low birth weight and still birth?

Answer 1

reduced O2 supply to foetus:

1. nicotine constricts blood vessels in placenta/umbilical cord
2. carbon monoxide binds to foetal Hb - reduces O2 transport

Question 2

why are pregnant women more at risk of anaemia?

Answer 2

1. haemodilution effect: both plasma volume and RBC mass increase during pregnancy, but plasma volume increases disproportionately
2. 3x higher physiological iron requirements: foetal demands, erythropoisis, maternal blood loss at delivery

Question 3

why does gestational diabetes occur?

Answer 3

increasing levels of progesterone and cortisone… increased insulin resistance to increase glucose supply to foetus… insufficient compensatory insulin rise… hyperglycaemia

Question 4

how does gestational diabetes affect foetal glucose and insulin levels

Answer 4

• high glucose in maternal blood crosses placenta to foetus… foetal hyperglycaemia
• foetus increases insulin levels to compensate… foetal hyperinsulinaemia

Question 5

how does hyperinsulinaemia (in gestational diabetes) affect the foetus

Answer 5

insulin has similar structure to growth promoters, causes:
1- macrosomia (causing labour complications)
2- organomegaly (esp. cardiomegaly)
3- erythropoiesis (causing polycythaemia)
4- polyhydramnios
5- increased risk of pre-term delivery

Question 6

how does gestational diabetes affect neonates

Answer 6

1) hypoglycaemia - after delivery, baby still has high insulin levels but no longer receives glucose from mother
2) transient tachypnoea of the newborn - high insulin causes decrease in pulomnary phospholipids… decreased foetal surfactant production

Question 7

what are the 3 diagnostic criteria of pre-eclampsia, and describe possible additional symptoms

Answer 7

1- >20 wks gestation
2- hypertension
3- proteinuria

other symptoms:

• headaches and visual disturbances
• epigastric pain
• sudden onset non-dependent oedema
• hyper-reflexia

Question 8

explain the likely pathophysiology behind hypertension in pre-eclampsia

Answer 8

i) abnormal placentation… incomplete remodelling of maternal uterine spiral arteries during trophoblast invasion… high resistance/low flow uteroplacental circulation due to fibrous, constricted arterioles…
ii) poor placental perfusion… pro-inflammatory protein release and diffusion into maternal circulation…
iii) vascular endothelial cell dysfunction… vasoconstriction and renal Na+ retention… hypertension and local vasospasms

Question 9

why is proteinuria a sign of pre-eclampsia?

Answer 9

local vasospasms in renal arteries… glomerular damage… oliguria and proteinuria

Question 10

why is epigastric pain a symptom of pre-eclampsia?

Answer 10

local vasospasms in hepatic arteries… liver injury and swelling… hepatic capsule distension/infarction

Question 11

why are visual disturbances a symptom of pre-eclampsia?

Answer 11

local vasospasms in retina arteries… blurred vision, flashing lights, scotoma

Question 12

why does generalised oedema occur in pre-eclampsia?

Answer 12

increased vascular permeability

Question 13

why should examination of the optic fundi and tendon reflexes be performed in pre-eclampsia patients

Answer 13

increased vascular permeability… cerebral oedema… raised ICP:

• papilloedema
• hyper-reflexia
• headaches, confusion and seizures (eclampsia)