2. Fetal Growth & Abnormalities of Human Development

Question 1

What is the definition of fetal growth?

Answer 1

Increase in mass that occurs between the end of embryonic period and birth

Question 2

What 2 components does fetal growth depend on?

Answer 2

• Genetic potential (mediated through growth factors e.g. Insulin-like GF)
• Substrate supply (derived from placenta which is dependent upon both uterine and placental vascularity)

Question 3

What are the 3 stages of normal fetal growth?

Answer 3

1. Cellular Hyperplasia
2. Hyperplasia and hypertrophy
3. Hypertrophy alone

Question 4

What are the relative fetal growth velocity at:

a. 14-15 weeks
b. 20 wks
c. 32-34 wks
d. >34 wks

Answer 4

a. 5g/day
b. 10g/day
c. 30-35g/day
d. growth rate decreases

Question 5

What is symphysis fundal height?

Answer 5

Distance over the abdominal wall from the pubic symphysis to the top of the uterus

Question 6

What are reasons for smaller than actual SFH?

Answer 6

• wrong dates
• Small for gestational age
• oligohydramnios
• transverse lie

Question 7

What are reasons for larger than actual SFH?

Answer 7

• Wrong dates
• molar pregnancy
• Multiple gestation
• Large for gestational age
• Polyhydramnios
• Maternal obesity
• Fibroids

Question 8

What are the cons of using SFH?

Answer 8

• Low detection rate (50-86%)
• Great inter-operator variability
• Influenced by a number of factors (BMI, fetal lie, amniotic fluid, fibroids)

Question 9

Why is dating by last menstrual period inaccurate?

Answer 9

Irregular period
Abnormal bleeding
Oral contraceptives
Breastfeeding

Question 10

Why is it important to correctly date?

Answer 10

• SGA/ LGA confusion
• Inappropriate inductions of labour
• Allow provision of steroids in preterm delivery

Question 11

Which type of pregnancy does not need to be dated by Crown Rump Length (CRL)?

Answer 11

IVF pregnancy

Question 12

When is head circumference (method of dating) used?

Answer 12

Only if 1st scan is done after 14 weeks (CRL>84mm)

Question 13

What are the 4 biometrical parameters used in Ultrasound assessment of fetal growth?

Answer 13

Biparietal Diameter
Head Circumference
Abdominal Circumference
Femur Length

• They are combined to give estimated foetal weight (EFW)

Question 14

What are the 4 biometrical parameters used for?

Answer 14

Normative growth curves are constructed, and EFW is expressed in centiles

Question 15

Which endocrine hormone is not present in foetus?

Answer 15

Prolactin

Question 16

When are iodothyronines produced from the thyroid?

Answer 16

By the 3rd trimester

Question 17

What are the 3 underlying principles of customized growth chart?

Answer 17

1. Adjusted to reflect maternal constitutional variation (height, weight, ethnicity, parity)
2. Standard free from pathological factors such as smoking and diabetes
3. Based on foetal weight curves derived from normal pregnancies

Question 18

What is cortisol’s effects on IGF2 gene expression?

Answer 18

Switch from IGF2 –> IGF1 gene expression in foetal liver

Question 19

What are the roles of IGF1 and IGF2 in conceptus?

Answer 19

• IGFs are mitogenic, stimulating fetal metabolism and coordinating feto-placental metabolism
• IGF1: growth of newborn
• IGF2: early embryonic development

Question 20

What are the direct effects of fetal insulin?

Answer 20

Adipose tissue

Proliferation of cells

Question 21

What is the role of fetal glucocorticoids?

Answer 21

Tissue differentiation and prenatal development of organs

• Lungs: maturation of surfactant
• Liver: control of glycaemia
• Intestines: maturation of expression of digestive enzymes and proliferation of villii

Question 22

What is the role of thyroid hormones?

Answer 22

Maturation of lungs

Nervous system

Question 23

Name 3 important growth factors for embryogenesis.

Answer 23

• EGFs (epidermal growth factors)
• TGFs (transforming growth factors)
• FGFs (fibroblast growth factors)

Question 24

Name an important enzyme involved in morphogenesis.

Answer 24

Embryonic cholinesterase (ChE)

Question 25

Name an important cytokine involved in implantation.

Answer 25

IL-1