PH: Congenital Malformations

Question 1

What is teratogenesis?

Answer 1

It may be induced when at least two conditions are met: teratogens must get into contact with the developing foetus, and the contact must be during the phase where the organ systems are in the process of being formed.

Question 2

When is teratogenesis most likely to affect development?

Answer 2

• 14 days gestation (conception to implantation): embryo well protected against maternal drugs, but not against radiation, for example.
• 14 days – 14 weeks (organogenesis): most vulnerable stage
• 14 weeks – delivery (foetal stage):

Question 3

What are some of the most common teratogens?

Answer 3

• Rubella – exposure before 16 weeks deafness or congenital heart defects
• Radiation – if exposure is after implantation
• Using a sauna – increases CNS defects
• Cocaine – microcephaly, SID, prematurity

Question 4

When is the most vulnerable period in pregnancy for the effects of teratogens?

Answer 4

14 days - 14 weeks (organogenesis phase)

Question 5

At what stage in pregnancy is an embryo well protected against maternal drugs, but not radiation?

Answer 5

Up to 14 days gestation (conception to implantation)

Question 6

How may maternal infection with rubella affect foetal development?

Answer 6

Exposure before 16 weeks deafness or congenital heart defects

Question 7

How may radiation affect foetal development?

Answer 7

Can cause developmental problems

Question 8

How may using a sauna affect foetal development?

Answer 8

Increases the risk of CNS defects

Question 9

How may using cocaine during pregnancy affect foetal development?

Answer 9

Microcephaly, SID, prematurity

Question 10

When may maternal rubella infection cause problems

Answer 10

Exposure before 16 weeks gestation –> deafness or congenital heart defects

Question 11

What triggers can cause neural tube defects in a foetus?

Answer 11

Folate deficiency, taking valproic acid, Trisomy 18 syndromes, and point mutations (MTHFR)

Question 12

What are the different types of genetic phenotype of Down’s Syndrome

Answer 12

Trisomy 21
Robertsonian Translocation (part of 21 is on top of 14)
Mosaic
Multiple chromosomes

Question 13

Why has their been a decline in neural tube defects recently?

Answer 13

> Improved screening (AFP and ultrasound)
Supplementation (folate)
Fortification (cornflakes, brussel sprouts)
Improved diet

Question 14

What congenital abnormalities are associated with Down’s Syndrome?

Answer 14

Heart defects: AV septal defect, ventricular septal defect, patent ductus arteriosus. 
Gi defects
Leukaemia
Hypothyroidism
Epilepsy
Alzheimer's disease

Question 15

How does foetal Down Syndrome affect the chance of miscarriage?

Answer 15

10-weeks to term, 43% of DS pregnancies will miscarry, and 16-weeks to term 23% of DS pregnancies will miscarry