Repro18 - Fetal Growth & Development

Question 1

6 features of fetal growth

Pregnancy Weeks
Pre-Embryonic
Embryonic
Fetal
Differential Growth
Body Proportions

Answer 1

1. ) Pregnancy Weeks - conception weeks (38)+ 2 = 40
   - calculated from date of last menstrual period
2. ) Pre-embryonic - weeks 1-2
   - teratogens here will destroy the pregnancy
3. ) Embryonic - weeks 3-8
   - organogenetic period, intense activity but small absolute growth
   - teratogens here causes structural abnormalities
4. ) Fetal - weeks 9-38
   - large growth and weight gain
   - early fetus = protein deposition, late fetus = adipose
   - only the brain is susceptible to teratogens
5. ) Differential Growth - of height and weight
   - CRL increases rapidly from pre-embryonic to early fetal
   - weight gain increases rapidly in mid/late fetal period
6. ) Body Proportions - change dramatically
   - at 9 weeks, head is approx half the CRL
   - body length and lower limb growth accelerates after

Question 2

Ante-natal assessment of fetal well-being

Fetal Movements
Measurements of Uterine Expansion
Ultrasound Scan
Classification of Birth Weights

Answer 2

1.) Fetal Movements

2. ) Measurements of Uterine Expansion
   - fundus to the pubic symphysis
3. ) Ultrasound Scan - routinely carried out at 20 weeks to assess fetal growth or fetal abnormalities
   - can be used early to calculate age, no of fetuses and also rule out ectopic pregnancy
4. ) Classification of Birth Weights - 3.5kg is average
   - <2.5kg suggests growth restriction
   - >4.5kg suggests macrosomia

Question 3

5 methods to estimate fetal age

Answer 3

1.) Last Menstrual Period (LMP) - prone to inaccuracy

2. ) Crown-Rump Length (CRL) - head to the buttocks
   - measured between 7-13 weeks to date the pregnancy and estimate the delivery date (EDD)
3. ) Biparietal Diameter (BPD) - distance betweeen parietal bones of the fetal skull
   - used to date pregnancies in T2 and T3
4. ) Abdominal Circumference and Femur Length
   - used in combination w/ BPD for dating and growth monitoring
   - also useful for detect any anomalies

Question 4

5 features of development of the respiratory system

Late Development
Pseudoglandular Stage
Canalicular Stage
Terminal Sac Stage
Breathing Movements

Answer 4

1. ) Late Development - embryonic development creates only the bronchopulmonary tree
   - functional sepcialisation occurs in the fetal period
2. ) Pseudoglandular Stage (8-16) - bronchioles form
   - duct system forms within bronchopulmonary segments
3. ) Canalicular Stage (16-26) - budding from bronchioles
   - formation of respiratory bronchioles
4. ) Terminal Sac Stage (26 - term)
   - bud from respiratory bronchioles
   - differentiation of type 1 and type 2 pneumocytes
   - baby delivered before week 26 will have ARDS
5. ) Breathing Movements - no functional purpsoe
   - conditioning of the respiratory musculature
   - filled with amniotic fluid so cannot breath

Question 5

4 features of development of the systems

Cardiovascular System
Urinary System
Nervous System
Sensory and Motor Systems

Answer 5

1. ) Cardiovascular System - oxygenated blood collected by umbilical vein
   - definitive fetal HR achieved at around 15 weeks
   - average fetal heart rate at term is 110-160
2. ) Urinary System - kidney function begins in week 10
   - not necessary for survival in utero
3. ) Nervous System - first to begin, last to finish
   - corticospinal tracts needed for coordinated voluntary movements to begin in the 4th month
   - brain myelination only begins in 9th month
4. ) Sensory and Motor Systems - no movement until the 8th week
   - practice suckling for post-natal life

Question 6

5 factors that can cause growth restriction

Placental Insuffiency
Hypoxia
Malnutrition
Congenital Defects
Others

Answer 6

1. ) Placental Insufficiency - e.g. pre-eclampsia
   - causes reduced blood flow
   - can lead to oligohydraminos (less kidney perfusion)
2. ) Hypoxia - asymmetrical growth restriction
3. ) Malnutrition - asymmetrical (or symmetrical)
4. ) Congenital Defects
   - causes symmetrical growth restriction

5.) Others - alcohol, smoking, drugs

Question 7

4 signs of fetal distress

Answer 7

1. ) Bradycardia (mainly)
   - HR measured using CTG (cardiotacogram)
   - could also be tachycardia
2. ) Reduced Fetal Movement
   - however baby could just be sleeping
3. ) Amniotic Fluid Volume
   - oligohydraminos: kidney dysfunction
   - polyhydraminos: difficulty swallowing

4.) Meconium in Amniotic Fluid