Foetal Growth

Question 1

List the phases of foetal growth (different to the phases of foetal development as seen in the next lecture).

Answer 1

• Phase 1 - 4-20 weeks: Increases in protein, weight and DNA content (cellular hyperplasia).
• Phase 2 - 20-28 weeks: Increases in protein and weight and lesser increases in DNA content (cellular hyperplasia + hypertrophy).
• Phase 3 - 28-30 weeks: Increases in protein and weight but no increase in DNA (hypertrophy).

Question 2

Define intrauterine growth restriction (IUGR).

Answer 2

Intrauterine growth restriction (IUGR) is failure of a foetus to achieve its growth potential.

Question 3

Define small for gestational age (SGA).

Answer 3

Small for gestational age (SGA) is birth weight lower than the 10th centile.

Question 4

Define large for gestational age (LGA).

Answer 4

Large for gestational age (LGA) is birth weight greater than the 90th centile.

Question 5

What is the Barker hypothesis?

Answer 5

The barker hypothesis states that most newborns with a low birth weight (but not IUGR) show catch-up growth in childhood, however newborns with IUGR are more likely to have lifelong impact.

Question 6

What si the reason for the Barker hypothesis?

Answer 6

IUGR newborns are less likely to show catch-up growth in childhood because the foetus shows particularly high neuroendocrine plasticity whilst in the womb, so it modifies its metabolism to suit the nutrient-restricted environment. These adaptations persists after birth.

Question 7

List 4 conditions that IUGR, SGA and LGA babies are more likely to develop in adulthood.

Answer 7

IUGR, SGA and LGA predispose to:

1 - Obesity.

2 - Type 2 diabetes.

3 - Stroke.

4 - Cardiovascular disease

Question 8

Why are mothers that were small for gestational age (SGA) be more likely to have SGA babies?

Answer 8

Mothers that were SGA are more likely to have SGA babies because of:

1 - Heritable changes in gene expression, such as DNA methylation, histone modification and micro RNA function.

2 - Changes to the number and function of maternal mitochondria.

Question 9

What are the major hormonal stimuli for placental and foetal growth?

Answer 9

IGF-1 and IGF-2 are the major stimuli for placental and foetal growth.

Question 10

List 4 maternal risk factors for IUGR.

Answer 10

1 - Maternal weight less than 45kg.

2 - Poor nutrition.

3 - Use of drugs, cigarettes, and alcohol.

4 - Maternal hypoxia.

Question 11

List 3 foetal risk factors for IUGR.

Answer 11

1 - Trisomy 18 (Edward’s syndrome).

2 - Congenital infection (CMV, toxoplasmosis, rubella etc.).

3 - Disorders of growth factors and thyroxine.

Question 12

What is the difference between primary and secondary placental risk factors for IUGR?

Answer 12

• Primary risk factors are due to abnormalities in the structure / formation of the placenta.
• Secondary risk factors are due to maternal factors that affect placental function such as:

1 - Hypertension.

2 - Chronic renal disease.

3 - Vasculitis.

4 - Prothrombotic disorders.

*There is also the potential problem multiple gestation, in which placental share is unequally divided.

Question 13

What is symphysio-fundal height?

How is it measured?

Answer 13

• Symphysio-fundal height is a measure of the size of the uterus used to assess fetal growth and development during pregnancy.
• It is measured from the fundus (top) of the mother’s uterus to the top of the mother’s pubic symphysis.

Question 14

If the symphysio-fundal height is found to be small, what follow-up assessments are done?

Answer 14

Following a small symphysio-fundal height measurement:

1 - A cardiotocograph is taken (recording the foetal heart rhythm).

2 - An umbilical artery doppler is taken to measure placental blood flow.

3 - Measurement of amniotic fluid volume (explained in a later card).

Question 15

List 6 maternal risk factors for SGA.

Answer 15

1 - Maternal age >40 years.

2 - Cocaine exposure.

3 - Low maternal weight gain during pregnancy.

4 - Previous SGA or stillbirth.

5 - Diabetes.

6 - Antiphospholipid syndrome (APLS).

Question 16

List the functions of the amniotic fluid.

Answer 16

1 - Amniotic fluid serves as a cushion for the growing fetus.

2 - Amniotic fluid facilitates the exchange of nutrients, water, and waste products between the mother and foetus.

Question 17

What is amniotic fluid composed of?

How is amniotic fluid used to assess foetal wellbeing?

Answer 17

• Amniotic fluid is composed of foetal urine.
• If blood flow to the foetus is compromised, blood flow to the foetal kidneys will reduce (and shunted to the brain and heart), reducing amniotic fluid production.
• Amniotic fluid volume can therefore be used to assess foetal wellbeing.

Question 18

What is gestational diabetes mellitus (GDM)?

What causes it?

Answer 18

• Gestational diabetes mellitus is any degree of glucose intolerance with its first onset during pregnancy.
• It is caused by insulin resistance due to hormonal and inflammatory changes during pregnancy. These include:

1 - hPL.

2 - TNF-alpha.

3 - Resistin.

• The insulin resistance increases with advancing gestation.

Question 19

List 5 risk factors for gestational diabetes mellitus (GDM).

Answer 19

1 - Previous GDM.

2 - Family history.

3 - PCOS.

4 - High BMI.

5 - Previous macrosomia (LGA >4.5kg).

6 - Steroid use.

7 - Polyhydramnios.

Question 20

List 4 maternal complications of gestational diabetes mellitus (GDM).

Answer 20

Complications of GDM include:

1 - Preeclampsia.

2 - pre-term labour.

3 - Diabetes in later life.

4 - The need for Caesarean section.

Question 21

List 5 foetal complications of gestational diabetes mellitus (GDM).

Answer 21

1 - Macrosomia (LGA. >4.5kg).

2 - Shoulder dystocia (a birth injury that happens when one or both of a baby’s shoulders get stuck inside the mother’s pelvis during labor).

3 - Polyhydramnios.

4 - Increased risk of perinatal mortality.

Question 22

List 3 treatments of gestational diabetes mellitus.

Answer 22

1 - Diet changes.

2 - Metformin.

3 - Insulin.