Week 9 - Fetal Growth and Development

Question 1

State what tests can be done to monitor fetal growth and development.

Answer 1

1. Ultrasound
2. Doppler ultrasound
3. Non-stress tests - monitors heart rate changes associated with fetal movements
4. Biophysical profile - which includes 5 variables to be measured
5. Vibroaccoustic stimulation - again monitoring fetal heart rate change
6. Contraction stress test
7. Fetal movements kick chart

Question 2

What accounts for most of the weight gain in the later stages of the fetal period?

Answer 2

After week 28, most of the weight gain is due to fetal adipose tissue deposition in subcutaneous and abdominal stores

Question 3

What is symmetrical growth restriction?

Answer 3

In which growth restriction is generalized and proportional

Question 4

What is asymmetrical growth restriction?

Answer 4

In which abdominal growth lags, and there is relative sparing of head growth

Question 5

When does asymmetrical growth restriction tend to occur?

Answer 5

In the last part of pregnancy when maternal, fetal or uteroplacental factors cause some deprivation of nutritional and oxygen supply to the fetus

Question 6

List some factors that have an impact on fetal growth.

Answer 6

1. Maternal nutrition and health
2. Efficiency of placenta
3. Adequate utero-placental blood flow
4. Genetic factors
5. Maternal parity - primaparous mothers have smaller babies than multiparous mothers
6. Maternal habits - e.g. smoking, drug abuse, etc
7. Also race, maternal height, maternal weight

Question 7

How may uteroplacental or fetoplacental circulations be assessed?

Answer 7

Doppler ultrasound

Question 8

What can compromise uteroplacental circulation?

Answer 8

1. Hypertension

2. Blood clots

Question 9

Why is 20 weeks a good time in pregnancy to have an ultrasound scan?

Answer 9

1. At this stage of pregnancy, the organ systems are developed and can be visualised and anomalies can be identified
2. If anomalies are seen, the pregnancy is still early enough for possible intervention or termination if appropriate
3. The inherent error in these measurements increases with gestational age such that as a dating tool, ultrasound becomes less accurate as the pregnancy proceeds

Question 10

State the errors of ultrasound in the first, second and third trimesters respectively.

Answer 10

1st trimester: +/- 1 week
2nd trimester: +/- 2 weeks
3rd trimester: +/- 3 weeks

Question 11

State some uses of ultrasound in obstetrics.

Answer 11

1. Determine the presence/absence of intrauterine pregnancy (or ectopic pregnancy)
2. Determine gestational age and measure fetal growth when compared against standard tables

Question 12

State some parameters that can be used to monitor fetal growth.

Answer 12

1. Abdominal circumference
2. Biparietal diameter
3. Crown-rump length
4. Femur length
5. Head circumference
6. Estimate fetal weight
7. Identify multiple pregnancies
8. Detect fetal anomalies (e.g. neural tube defects) or placental anomalies (e.g. placenta praevia)
9. Measurement of amniotic fluid
10. Identify maternal pelvic anomalies
11. Guide for needle in amniocentesis

Question 13

Why are folic acid supplements recommended for pregnant women?

Answer 13

Reduce the risk of neural tube defects

Question 14

When are routine blood tests of alpha-fetoprotein done?

Answer 14

Between 15-19 weeks of gestation when levels are at their highest

Question 15

What can raised alpha-fetoprotein levels indicate?

Answer 15

1. Open neural tube defect

2. Multiple pregnancies

Question 16

How early can the fetal heart beat be observed with transvaginal ultrasound?

Answer 16

As early as 5-6 weeks

Question 17

When can you hear the fetal heart beat with a Doppler stethoscope?

Answer 17

10-12 weeks

Question 18

When can you hear the fetal heart beat with a plain stethoscope?

Answer 18

18-20 weeks

Question 19

What is the average fetal heart rate at term?

Answer 19

140-160 beats per minute

Question 20

At what stage are fetal respiratory movements evident by sonography?

Answer 20

From about 12 weeks, fetal respiratory movements seen by sonographic evaluation

Question 21

At what gestational age does surfactant production begin?

Answer 21

Surfactant production begins at 20 weeks, but increases dramatically after 30 weeks, reaching significant levels at about 34 weeks

Question 22

What can be done antenatally to reduce risk of respiratory distress syndrome in premature infants?

Answer 22

Steroid therapy can be given to women ante-natally who are at risk of pre-term delivery: reduces the risk of RDS by 50% by promoting production of surfactant

Question 23

What fetal landmark is used to assess fetal head position in the birth canal?

Answer 23

Fetal fontanelles

Question 24

If an epidural is used for pain relief, what spinal segments are blocked?

Answer 24

T9-S4

Question 25

Why is the patient with an epidural at risk of hypotension?

Answer 25

Lumbar sympathetic outflow blockade prevents vasoconstriction

Question 26

Define post-partum haemorrhage.

Answer 26

Blood loss of greater than 500 ml after vaginal delivery

Question 27

What physiological mechanism exists to prevent PPH?

Answer 27

Strong contractions after the 3rd stage of labour contract the uterus down, achieving closure of the “living ligature” - the unusual criss-cross arrangement of myometrial fibres, clamping the arterial supply to the placental bed in the endometrium

Question 28

If the uterus is firm on palpation with continuous bleeding, what other cause should you consider?

Answer 28

1. Laceration/trauma to the genital tract

2. Retained placenta