Fetal Growth and Development Flashcards Preview

ESA 4 - Reproductive System > Fetal Growth and Development > Flashcards

Flashcards in Fetal Growth and Development Deck (112):
1

What is happening in the pre-embryonic period? 

Lots of cell division 

2

When is the pre-embryonic period? 

Weeks 1-2

3

What happens in the embryonic period? 

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

4

When is the embryonic period? 

Weeks 3-8

5

What is the embryonic period the stage of? 

Greatest morphological change

6

What is the embryonic period characterised by? 

Intense activity, as it is the organogenic period 

7

What is meant by the organogenic period? 

Building detailed stuctures from a few cells 

8

How much absoloute growth is there in the embryonic period? 

Very little 

9

What is the fetal period? 

The period involving preperation for the transition to independant life after birth 

10

When is the fetal period? 

Weeks 9-38

11

What is being grown towards in the fetal period? 

The ability to survive after delivery 

12

What happens to the rate of growth and weight gain in the fetal period? 

They accelerate

13

How do the body proportions change in the fetal period? 

At 9 weeks, the head is approx half of the crown-rump length, but thereafter the body length and limb growth accelerate, becasue development is in a head-to-tail fashion 

14

When does crown-rump length increase rapidly? 

In the pre-embryonic, embryonic, and early fetal period 

15

What happens to weight gain throughout gestation? 

It is slow at first, and then increases rapidly in the mid- and late-fetal periods 

16

How much weight gain is there in the embryo? 

Little weight gain, placental growth is most significant, and constitutes a large % of the weight gain

17

What is responsible for the weight gain in the early fetus? 

Protein deposition to build the growing muscles 

18

What is responsible for the weight gain in the late fetus? 

Adipose deposition 

19

What is the importance of adipose deposition in the late fetus? 

Prepares it for life after the uterus 

20

21

Why is adipose deposition required for life after the uterus? 

Helps manage body temperature 

22

What happens in an ante-natal assessment of fetal wellbeing? 

  • Mother asked about fetal movements
  • Regular measurements of uterine expansion
  • Ultrasound scans

 

23

Why is it useful to ask the mother about fetal movements? 

Mother will come to know the rhythm of the movements that the baby takes, and so can detect if their is a change

 

24

How is uterine expansion measured? 

Symphysis-fundal height measured by palpation of pubic symphysis and fundus of uterus 

25

Why are ultrasounds used in pregnancy rather than x-rays? 

Because they are safe, and we don't want to do anything that can damage the vulnerable fetus 

26

What can ultrasound scans be used for in early pregnancy? 

  • Calculate age
  • Rule out ectopic pregnancies 
  • Check number of fetuses
  • Check fetal heart rate 

 

27

Why is it important to check the fetal heart rate in early pregnancy? 

Because fetal bradycardia can be a sign of impending fetal demise 

28

When are ante-natal ultrasounds routinely performed? 

20 weeks

 

29

What is being looked for at the 20 week ultrasound? 

Fetal anomalies 

 

 

30

Why can fetal anomalies be assessed at a 20 week ultrasound? 

All major body systems have grown, so there are no further structural changes 

31

What systems can be assessed at the 20 week ultrasound? 

  • Brain ventricles
  • Heart chambers
  • Spinal cord development 

 

32

Why is it important to check for spinal cord development at the 20 week ultrasound? 

Look for signs of spina bifida

33

How can fetal age be estimated? 

  • LMP
  • Developmental criteria

 

34

How is fetal age calculated from LMP? 

Find out date of 1st day of LMP. and estimate ovulation from normal cycle length 

35

What is the problem with calculating fetal age from LMP? 

Prone to inaccuracies 

36

Why is the calculation of fetal age from LMP prone to inaccuracies? 

  • Cycle length can vary
  • Implantation bleeding happens at 14 days

 

37

What is the advantage of fetal aging using developmental criteria? 

Allows accurate estimation of fetal age 

38

What developmental criteria can be used to measure fetal age? 

  • Crown-rump length
  • Bi-parietal diameter
  • Abdominal circumference and femur length
  • 3- or 4-D USS

 

39

When is crown-rump length used to estimate fetal age? 

Betwen 7 and 13 weeks

 

40

What happens after 13 weeks, regarding using crown-rump length to estimate fetal age? 

The relationship is less predicatble 

41

What is the bi-parietal diameter? 

The distance between parietal bones of the fetal skull 

42

How is the measurement of bi-parietal diameter used? 

In combination with other measurements to date pregnancies in T2 and Y3

43

Other than fetal aging, what is the use of bi-parietal diameter? 

Can see ventricular system of the brain, therefore can look for any malformations

44

How is abdominal circumference and fermur length used? 

  • In combination with BPD for dating and growth monitoring
  • Anomaly detection 

 

45

What is the difference between 3D and 4D USS? 

4D includes movement 

46

How is 3D and 4D USS used? 

As a complimentary tool, not likely to replace standard USS 

47

What abnormality can be seen on 3D and 4D USS? 

Can see cleft lip and palate 

48

What birth weight is considered to be average? 

3500g 

49

What birth weight suggests growth restriction? 

<2500g 

50

What birth weight is considered to be macrosomia? 

>4500g

51

What is the most common cause of macrosomia? 

Poorly controlled maternal diabetes 

52

Are all factors that influence birth weight pathological? 

No

53

Why may babies have a low birth rate? 

  • Premature, and they are the normal weight for their gestational age 
  • Constitutionally small
  • Suffered growth restriction 

 

54

Why may a baby be constitutionally small? 

Small mothers tend to have small babies 

55

Why do we want to try and identify babies that have suffered growth restriction during antenatal screening? 

Because it is associated with neonatal morbidity and mortality 

56

Why do the lungs develop relatively late? 

Beause they have no function during embryonic life

57

What does embryonic development create, regarding the lungs? 

Only the bronchopulmonary tree

58

What is the respiratory diverticulum made of? 

Endoderm tissue that buds off from the primitive gut tube 

59

How is the respiratory diverticulum and the gut tube seperated? 

Tracheoesophageal septum is formed to seperate the tracts 

60

When does functional specialisation of the respiratory system occur? 

In the fetal period 

61

What are the stages of functional specialisation of the lungs? 

  • Pseudoglandular stage
  • Canalicular stage
  • Terminal sac stage

 

62

When is the pseudoglandular stage? 

Weeks 8-16 

63

What happens in the pseudoglandular stage? 

Begin to develop a series of primitive ducts within the broncopulmonary segments created during the embryonic periods, getting down to the formation of bronchioles 

64

When is the canalicular stage? 

Weeks 16-26

65

What happens in the canalicular stage? 

Formation of respiratory bronchioles 

66

How are respiratory bronchioles formed in the canalicular stage? 

Bud off from the bronchioles formed during the pseudoglandular stage 

67

When is the terminal sac stage? 

Week 26-term

68

What happens in the terminal sac stage? 

Terminal sacs begin to bud off from the respiratory bronchioles, and differentiation of type I and II pneumocytes

69

What do type II pneumocytes produce? 

Surfactant

70

What does the terminal sac stage allow? 

The respiratory system to function as a gas exchange membrane 

71

What does the fetal development of the lungs have major implications for? 

Pre-term survival 

72

Why does the development of the lungs have major implications for pre-term survival? 

Because the baby cannot surviva without a membrane for exchanging gas

73

Why can't the threshold of viability be continuously pushed back? 

Since there is a limit beyond which the lungs will not be sufficiently developed to sustain life 

74

When is a fetus viable? 

Only once the lungs have entered the terminal sac stage of development, at 24 weeks

75

What often affects infants born prematurely? 

Respiratory distress syndrome

76

What causes respiratory distress syndrome? 

Insufficient surfactant production due to there not being enough type II pneumocytes 

77

What can be done if a pre-term delivery is unavoidable or inevitable? 

Give glucocorticoids treatment to mother

78

How does giving glucocorticoid treatment to the mother help prevent respiratory distress syndrome? 

Pushes fetal type II pneumocytes to produce more surfactants, allowing for mitigation of some of the consequences of pre-term delivery 

79

How is gas exchange conducted during T2 and T3? 

At the placenta 

80

When must the lungs be prepared to assume the full burden of gas exchange? 

At birth

81

How are the lungs prepared to take the full burden of gas exchange at birth?

Breathing movements 

82

What is the importance of breathing movements of the fetus? 

Conditions the respiratory musculature- the diaphragm and intercostals

83

What does the fluid filling the lungs contain?

Growth factors 

84

What is the fluid filling the lungs crucial for? 

Normal lung development 

85

What is the fetal cardiovascular system arranged to do? 

Ensure that oxygenated blood collected by the umbilical vein at the placenta is circulated around the fetus

86

When is the definitive fetal heart rate reached? 

Around 15 weeks

87

What is the definitive fetal heart rate? 

110-140BPM

88

What is fetal bradycardia associated with? 

Fetal demise

89

When does fetal kidney function begin? 

In week 10 

90

What is the importance of fetal urine? 

It is a major contributor to amniotic fluid volume 

91

Theorectically, what would happen if a fetus had no kidney function? 

Fetal kidney function is not necessary for survival in utero, but without it there is oligohydramnios

92

Why is fetal kidney function not necessary for survival in utero? 

Because placenta is doing the renal function 

93

What is oligohydramnios? 

Too little amniotic fluid 

94

What could oligohydramnios be due to? 

Placental insufficiency 

95

Why can placental insufficiency cause oliohydramnios? 

Because very early in pregnancy, placental membranes are responsbile for AF production 

96

Give an example of a condition that would give fetal renal impairment?

Bilateral renal agenesis, which is incomptaible with life 

97

What is polyhydramnios? 

Too much amniotic fluid 

98

What can cause polyhydramnios? 

  • Sometimes idiopathic
  • Fetal abnormality, e.g, inability to swallow 

 

99

How does the timing of nervous system development compare to the other systems? 

First to begin development, last to finish 

100

When does fetal movement begin? 

8th week 

101

What happens, regarding fetal movements, from the 8th week onwards? 

A large repertoire of movements development 

102

What is the importance of the development of a large repertoire of movements in fetal life? 

Practicing for post-natal life 

103

Give two examples of movements a fetus might perform to practice for post-natal life

  • Suckling
  • Breathing 

 

104

When does corticospinal tract development begin to form? 

In the 4th month 

105

What are corticospinal tracts required for? 

Coordinated voluntary movements

106

When does myelination of the brain begin? 

In the 9th month 

107

What evidence is there for corticospinla tract myelination being incomplete at birth? 

Increasing infant mobility in the 1st year, with babies not being able to walk until a year old

108

What is the implication of development of the fetal nervous tract? 

'Quickening' 

109

What is quickening? 

Maternal awareness of fetal movements 

110

When does maternal awareness of fetal movements begin? 

17 weeks onwards, but later in first pregnancy, earlier in later pregnancies 

111

How can quickening be used clinically? 

It is a low cost, simple method of ante-partum fetal surveillance 

112

How can quickening be used in fetal surveillance?

Can report changes in pattern of movement, and reveal fetuses requiring follow up