Fetal growth

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 does fetal growth depend on?

Answer 2

Genetic potential

Substrate supply

Question 3

What are the 3 phases of normal fetal growth?

Answer 3

Cellular hyperplasia

Hyperplasia and hypertrophy

Hypertrophy alone

Question 4

What is the pattern of fetal growth?

Answer 4

14-15 wks: 5g /day

20 wks: 10 g/day

32-34 wks: 30-35g/day

> 34 wks: growth rate decreases

Question 5

What techniques can be used for assessing fetal growth?

Answer 5

Symphysis fundal height (SFH)

Ultrasound crown-rump length - the gold standard

Note:
It should be done towards the end of the 1st trimester as fetal growth is less varied then

Question 6

What’s the technique of SFH?

Answer 6

distance over the abdominal wall from the symphysis to the top of the uterus

Question 7

What are the pros and cons of SFH?

Answer 7

Pros:
Simple
Inexpensive

Cons:
Low detection rate: 50-86%

Great inter-operator variability

Influenced by a number of factors (BMI, fetal lie, amniotic fluid, fibroids)

Question 8

How is fetal growth assessed by ultrasound?

Answer 8

Biparietal diameter (BPD), Head circumference (HC)
Abdominal circumference (AC) Femur length (FL)
and their combination (EFW)

Question 9

What is the use of ultrasound assessment of fetal growth?

Answer 9

Assessment of fetal “wellness” not just size

Looking at trends in growth from centile graphs

Predicting fetal metabolic compromise

Anticipating the need to deliver prematurely

Question 10

What are the maternal factors influencing fetal growth?

Answer 10

Poverty: younger mothers and less education

Age: 16-35 is best

Drug use: developmental defects, still births, premature delivery, LBW, addiction

Weight

Disease:
hypertension
diabetes
coagulopathy

Smoking and nicotine

Alcohol: brain development

Diet

Prenatal depression

Environmental toxins

Question 11

What are the feto-placental factors influencing fetal growth?

Answer 11

Genotype – genetic potential

Gender (B>G)

Hormones

Previous pregnancy - 2nd child likley to be bigger than the 1st

Question 12

What are the 3 features of a customised growth chart?

Answer 12

Adjusted to reflect maternal constitutional variation maternal ht, wt, ethnicity, parity

Optimised by presenting a standard free from pathological factors such as diabetes and smoking

Based on fetal weight curves derived from normal pregnancies

Question 13

What can a small SFH indicate?

Answer 13

wrong dates

small for gestational age

oligohydramnios

Question 14

What can a large SFH indicate?

Answer 14

wrong dates

molar pregnancy

multiple gestation

large for gestational age

Polyhydramnios

Maternal obesity

Fibroids

Question 15

What is the definition of low birth weight, very low birth weight and extremely low birth weight??

Answer 15

LBW = Less than 2,500g at delivery.
VLBW = Less than 1,500g at delivery.
ELBW = Less than 1,000g at delivery.

Question 16

What are centile charts useful for?

Answer 16

Plotting serial measurements to monitor that the baby is growing consistently along the same centile

Question 17

Why is data on fetal weight throughout pregnancy potentially wrong?

Answer 17

Data is collected from miscarriages, so there is potential for them to have a low birth weight.

Question 18

Why is correct dating important?

Answer 18

It can determine whether the baby is judged to be low or high weight for its age

This effects decisions like whether to have a cesarian section or whether to try and resuscitate a pre term baby

Question 19

What is the definition of Intrauterine growth restriction (IUGR)

Answer 19

Failure of the infant to achieve its predetermined (genetic) potential for a variety of reasons

Question 20

What is the definition of Small for gestational age (SGA)?

Answer 20

The infant has a birth weight <10th centile (also called ‘Small for dates’).

Question 21

Why is it important to distinguish between LBW and IUGR?

Answer 21

LBW may simply be LBW because they were pre-term

IUGR has increased risk of morbidity and mortality

Question 22

How should IUGR be defined?

Answer 22

The term IUGR should only be used for fetuses with definite evidence that growth has altered.

The serial measurements should show that the infant is not growing ‘along a centile’, but is growing less than would be expected.

Question 23

When does IUGR develop?

Answer 23

In the 2nd and 3rd trimesters when growth is fastest

Question 24

What are the short term consequences of IURG?

Answer 24

Respiratory distress
Intraventricular haemorrhage
Sepsis
Hypoglycaemia
Necrotising enterocolitis
Jaundice
Electrolyte imbalance

Question 25

What are the medium term consequences of IURG?

Answer 25

Respiratory problems
Developmental delay
Special needs schooling

Question 26

What are the long term consequences of IURG?

Answer 26

Fetal programming

Question 27

What is fetal programming?

Answer 27

A number of organ structures and associated functions undergo programming during embryonic and fetal life

This determines the set point of physiological and metabolic responses that carry into adulthood.

Hence, any stimulus or insult at a critical period of embryonic and fetal development can result in developmental adaptations that produce permanent structural, physiological and metabolic changes.

Thereby predisposing an individual to cardiovascular, metabolic and endocrine disease in adult life

Question 28

What is strongly associated with IUGR? Explain this link

Answer 28

Pre-eclampsia

The main cause of pre-eclampsia is diminished remodelling of the spiral arteries by cytotrophoblast

This causes decreased blood flow and hence decreased nutrient supply to the placenta and fetus.

Question 29

What is the treatment for IUGR and IUGR with pre-eclampsia?

Answer 29

Corticosteriods should be administered (if not already given) at gestations < 36 weeks in order to improve neonatal wellbeing, notably the development of the lungs.

For pre-eclampsia because the main issue is with the placenta, the ‘treatment’ is delivery