Fetal development

Question 1

When can a fetus respond to sound?

Answer 1

The cochlea and peripheral sensory end organs have developed by 24 weeks.
Auditory brain responses (ABRs) first appear between 26 and 28 weeks in preterm infants and cannot be detected before 25 weeks.
Minimum stimulus is 65 dB at 25 weeks.

Question 2

The umbilical artery S/D ratio decreases with: fetal age, bradycardia, IUGR, HLHS?

Answer 2

Fetal age

Question 3

Highest PO2 in the fetus

Answer 3

From fetal physiology:
a. Inferior vena cava (26)
b. Ductus arteriosis (52)
c. Right Ventricle (??)
d. Descending aorta (58)

Question 4

Normal AF volume @ 10 weeks

Answer 4

30 mL

Question 5

Normal AF volume @ 16 weeks

Answer 5

200 mL

Question 6

Normal AF volume @ 32 weeks

Answer 6

800 mL

Question 7

Normal AF volume @ 40 weeks

Answer 7

500 mL

Question 8

What are the 6 pathways of amniotic fluid turnover?

Answer 8

Fetal urine production 700 ml/day
Fetal swallowing 700 ml/day
Fetal lung secretions 200 ml/day
Intramembranous (across placenta/cord/fetal skin) 200-500 ml/day
Transmembranous (across uterus) 10 ml/day
Secretions (oral/nasal) 25 ml/day