Fetal growth

Question 1

A definition of fetal growth

Answer 1

The increase in mass that occurs between the end of the embryonic period and birth.

Question 2

What does Symphysis Fundal Height identify?

Answer 2

distance between the pubic symphysis and the top of the uterus
Reflects generic changes in uterine size

Question 3

What can lower values from SFH result from?

Answer 3

wrong last menstrual period date, the baby in a transverse lie, or complications including oligohydramnios (low levels of amniotic fluid) or a baby that is small for gestational age (SGA)

Question 4

What can higher values from SFH result from?

Answer 4

wrong last menstrual period date, multiple pregnancy, or maternal obesity.

Question 5

How is uterus position at week 40 different to week 38?

Answer 5

It’s lower believe it or not

Question 6

What are possible complications?

Answer 6

molar pregnancy, fibroids, polyhydramnios or a baby that is large for gestational age (LGA).

Question 7

What are the uses and problems with SFH?

Answer 7

may identify gross changes in size, and hence gross complications
generally of limited use, thanks to the many confounders, which include the problems listed above, as well as considerable inter-operator variability.

Question 8

How do fetal weight and height changes differ?

Answer 8

weight continues to increase throughout pregnancy

fetal weight changes less later in, got a plauetue r shape.

Question 9

What are the two primary components for fetal growth?

Answer 9

genetic potential

Substrate supply

Question 10

What is genetic potential?

Answer 10

• derived from both parents, size of fetus reflectionof parents mediated by factors under genetic control e.g. IGF1

Question 11

What is substrate supply?

Answer 11

• sufficient nutrients are essential to achieve genetic potential. This is primarily based on the placenta which is dependent upon both uterine and placental vascularity.

Question 12

What are the 4 biometrical parameters of fetal growth?

Answer 12

Biparietal diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC) and Femur Length (FL). They are combined to give the Estimated Fetal Weight (EFW).

Question 13

What has been constructed from these ultrasound measurements?

Answer 13

Normative growth curves expressed in centiles

Question 14

How are biometrical parameters used clinically?

Answer 14

identify a normal intrauterine growth and detect risk of obstetric and neonatal complications.

Question 15

Which measurement is most important?

Answer 15

In many cases, it is not single measurements that are most important, but sequential measurements.

Question 16

What are the underlying principles for customised fetal graphs?

Answer 16

They are based on fetal weight curves for normal pregnancies.

The are adjusted to reflect maternal constitutional variation e.g. maternal height, weight, ethnicity, parity.

They are optimised by presenting a standard free from pathological factors such as diabetes and smoking.

Question 17

What is the overall average rate at which an infant gains weight?

Answer 17

14-15 wks: 5g /day
20 wks: 10 g/day
32-34 wks: 30-35g/day
>34 wks: growth rate decreases
Note that the final point, of decreased velocity towards the end of pregnancy, does not agree well with the early data in Figure 6.3, showing that the miscarriage data is not reliable.

Question 18

What are the 3 main phases of normal fetal growth?

Answer 18

Cellular hyperplasia (increased cell numbers): 4-20 weeks
Hyperplasia and hypertrophy (increased cell size): 20-28 weeks
Hypertrophy dominates: 28-40 weeks

Question 19

When is the main increase in weight?

Answer 19

Final trimester so hypertrophy key.