Lecture 16 - Fetal Development

Question 1

Foetal period

Answer 1

Growth and physiological maturation of the structures created during the embryonic period

9 weeks to term

Greatest growth and weight gain

Question 2

Crown rump length and weight gain

Answer 2

CRL - increases rapidly in the pre-embryoinc, embryonic and early gale tail periods

Weight gain - slow at first and increases rapidly in mid to late football period

Question 3

Early foetus

Answer 3

Protein deposition and muscle development

Question 4

Late foetus

Answer 4

Adipose deposition for metabolism and heat regulation

Question 5

Head proportion

Answer 5

9th week - 50%

38th week - 25%

Question 6

Ante-natal assessment

Answer 6

At 20 weeks
Foetal movements
Ask mother
Symphysis fundal height - uterine expansion
(Normally at umbilicus at 20 weeks and xiphisternum at 38 weeks )

Question 7

Factors affecting symphysis fundal height

Answer 7

Polyhydraminios

• a lot of amniotic fluid
• over estimation

Oligohydramnios

• lack of amniotic fluid
• under estimation

Intrauterine growth restriction - smaller baby

Near term - faoetsl head engages the pelvis therefore SFH decreases

Question 8

USS

Answer 8

Safe
Used to calculate age
Rule our ectopic pregnancy and number of foetuses
Assess foetal growth and anomalies

Question 9

Estimating foetal age

Answer 9

Last menstrual period - innacurate
Conception 2 weeks after last menstrual cycle

CRL
Biparietal diameter

Question 10

Crown rump length

Answer 10

Measured between 7 and 13 weeks to date the pregnancy and estimate the date of delivery

Question 11

Biparietal diameter

Answer 11

Distance between the parietal bones in the foetal skull

• during 2nd and 3rd trimester

(Later in pregnancy CRL less accurate)

Question 12

Abdominal circumference and femur length

Answer 12

Us3d with biparietal diameter for dating and growth monitoring

Width of widest part of the abdomen and length of femur

Question 13

Birth weight

Answer 13

Average 3500g

Growth restriction - less than 2500g

Macrosomia - more than 4500g

Question 14

Low birth weight reasons

Answer 14

Premature
Constitutionally small
Growth restriction

Question 15

Respiratory system

Answer 15

Develop relatively late

Embryonic development - bronchopulmonary tree development

Foetal development - functional specialisation

Question 16

Pseudoglandular stage

Answer 16

Week 8 - 16

Duct system begins to form within the bronchopulmonary segments creating bronchioles

Question 17

Canalicular stage

Answer 17

Week 16 - 26

Formation of respiratory bronchiole

Budding from the bronchioles

Question 18

Terminal sac stage

Answer 18

Week 26

Terminal sacs begin to bud from the respiratory bronchioles to produce alveoli

Differentiation of type I and type II pneumocytes

Production of surfactant from type II pneumocytes

Question 19

Lungs during the 2nd and 3rd trimester

Answer 19

Gas exchange occurs at the placenta

Breathing movements - conditioning of the respiratory musculature

Fluid filled - amniotic fluid contains mediators that promoted the differentiation on pneumocytes

Question 20

Pre term survival

Answer 20

Viable after 24 weeks after surfactant is made in the terminal sac stage

Question 21

Respiratory distress syndrome

Answer 21

Often affects premature babies

Lack of surfactant

• when preterm birth is unavoidable e.g. in sever preeclampsia can give glucocorticoids to mother which increases surfactant production in the foetus

Question 22

Foetal heart rate

Answer 22

100 -160

Around 15 weeks

Foetal Bradycardia - foetal distress due to hypoxia

Question 23

Urinary system

Answer 23

Foetal kidney function occurs at 10 weeks

Foetal urine contributes to the amniotic fluid volume

Without kidney function - oligohydramnios

Question 24

Oligohydramnios

Answer 24

Too litte amniotic fluid
Placental insufficiency
Foetal renal impairment

Question 25

Polyhydramnios

Answer 25

Too much amniotic fluid

Foetal abnormality e.g. Inability to swallow e.g. tracheal oesophageal fistula

Question 26

Nervous system

Answer 26

First to begin development and last to finish developing

Corticospinal tracts required for coordinated voluntary movements develop in 4th month

Myelination of brain - 9 months

• can’t walk or control voiding

Question 27

Motor movements

Answer 27

Begin after 8 weeks

Practising movements e.g sucking thumb

Question 28

Quickening

Answer 28

Maternal awareness of movement from 17 weeks