Small babies Flashcards

1
Q

How does growth occur in the embryonic period of development?

A

Absolute growth of embryo is minimal but morphogenesis of the body shape and development of all the organs begin in this stage; majority of growth occurs in the placenta. This occurs via action of IGF-2 hormone.

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2
Q

What is the mechanism of growth at 0-20 weeks gestation?

A

Hyperplasia which occurs via cleavage to increase cell number

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3
Q

How does growth occur in the foetal period of development?

A

Accelerated growth and weight gain. In the early foetal period, weight gain occurs due to protein deposition. In the late foetal period, weight gain occurs due to fat deposition. This occurs via action of IGF-1 hormone.

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4
Q

What is the mechanism of growth at 20-28 weeks?

A

Combination of hyperplasia via cleavage and hypertrophy of existing and developing structures.

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5
Q

What is the mechanism of growth at 28 weeks-term?

A

Hypertrophy of present structures such as the organs.

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6
Q

What are the different methods for dating pregnancy?

A

Crown-rump length, symphysis-fundal height, head circumference, femur length

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7
Q

What is used to determine gestational age before 24 weeks?

A

Crown-rump length- this the length of the foetus from head to bottom only used between 7-13 weeks in first trimester.
From 13 weeks: Head circumference and femur length that can be used to term.

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8
Q

How many ultrasounds do pregnant women receive in a standard pregnancy?

A

2 ultrasounds
One at 12 weeks to rule out ectopic pregnancy and number of foetus
One at 20 weeks to assess foetal growth and anomaly and view the fully formed heart chambers.

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9
Q

What is the CRL at 9 weeks?

A

5cm

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10
Q

What is the CRL at 38 weeks?

A

36 cm

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11
Q

How is foetal age estimated?

A

LMP (LAST MENSTRUAL PERIOD) which can be inaccurate
Abdominal circumference and femur length for detecting anomalies
Ideally use developmental criteria for accurate estimation

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12
Q

How is foetal wellbeing assessed in pregnancy?

A

Foetal movement, obstetric/ultrasound scan, biochemical tests and measurement of uterine expansion from symphysis-fundal height

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13
Q

What are the biochemical tests?

A

Levels f
hCG: important in first trimester
human placental lactogen: for metabolic regulation of foetal insulin sensitivity
Oestriol
A-fetoprotein

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14
Q

What is oestriol?

A

Pregnancy form of oestrogen which is important for triggering the development of the organs in the foetus.

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15
Q

What is a-fetoprotein?

A

Produced by embryonic hepatocytes which transport bilrubin, drugs and heavy metal ions in foetal blood circulation. It has a poor predictive value for low foetal growth and is expensive.

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16
Q

What is the issue with symphysis-fundal height?

A

Unreliable for detecting intrauterine growth restriction but can track uterine expansion to gauge foetal growth and is cheap and easy.

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17
Q

How does body proportion of the foetus change in pregnancy?

A

Head makes up the majority of CRL in early pregnancy, and proportions change as there is more accelerated lower limb and body length growth.

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18
Q

Why is nutrition important in pregnancy?

A

To support foetal development, which is reliant on maternal stores from the moment of conception. Malnutrition not only causes issues in utero, such as intrauterine growth restriction (both symmetrical and asymmetrical) but also lead to increased incidence of chronic disease in adulthood.

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19
Q

What is the Barker hypothesis?

A

Foetal responses to inadequate nutrition due to maternal factors or the placenta will increase the likelihood of chronic disease in adulthood.

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20
Q

What are the important hormones for foetal growth?

A

Insulin
IGF-1
IGF-2
Leptin
Epidermal growth factor and Transforming growth factor-alpha

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21
Q

What is the role of insulin in foetal growth?

A

Maternal insulin which cannot cross placenta but acts on placental receptors to stimulates the uptake of glucose in the foetus; foetal pancreas can also produce insulin.
This will increase foetal mass and create glycogen stores to be utilised during maximum demand in late gestation.

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22
Q

What is IGF-1?t

A

Insulin-like growth factor 1 which IS released via action of growth hormones to promote bone and tissue development. It increases the sensitivity of the cells to insulin and action of protein synthesis and fat deposition for we

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23
Q

When are IGF-1 levels most dominant?

A

Nutrient dependent and act primarily in the second and third trimester

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24
Q

What is IGF-2?

A

Insulin-like growth factor 2 which regulates foetal development

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25
Q

When are IGF-2 levels most dominant?

A

Nutrient independent and act primarily in the 1st trimester for morphogenesis.

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26
Q

What is leptin in foetal development?

A

Cytokine produced by the placenta which is important for foetal growth.

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27
Q

What is the role of leptin in adults?

A

Hormone produced by adipose tissue which inhibits hunger in adults.

28
Q

What is the function of EGF?

A

Proliferation of cells, espeically fibroblast and epithelial cells and regulation of foetal growth via intracellular signalling.

29
Q

What is the function of TGF-alpha?

A

Type of EGF for control and proliferation of glial and Schwann cells.

30
Q

What is average birth weight?

A

3.5kg but the normal range is 2.5kg-3.5kg

31
Q

What does low birth weight indicate?

A

Below 2.5kg due to intrauterine growth restriction

32
Q

Why does low birth weight occur?

A

Malnutrition
Infection with rubella, toxoplasmosis and cytomegalovirus
Maternal hypertension eg pre-eclampsia
Pre-term baby
SOME BABIES ARE CONSITUTIONALLY SMALL AND HEALTHY

33
Q

What is important in ruling out IUGR?

A

Normal trajectory of growth as expected without stagnation, even if weight is below expected.

34
Q

Which infections increase IUGR?

A

Rubella (german measles) toxoplasmosis and cytomegalovirus

35
Q

What does high birth weight indicate?

A

Gestational diabetes due to physiological change of insulin resistance in pregnancy because of higher cortisol, oestrogen and progesterone leading to higher blood glucose. Excess glucose uptake by baby results in macrosomia, which increases labour complications for mother and increases the risk for metabolic syndrome in neonate.

36
Q

What factors influence birth weight?

A

Maternal nutrition with low/high BMI
Maternal hypertension
Smoking/alcohol intake
Chronic conditions
Multiple pregnancy

37
Q

Which chronic conditions affect birth weight?

A

Anaemia: increases hypoxia risk and IUGR and low birth weight
Hypertension: causes IUGR and lower birth weight due to less placental blood flow because maternal blood supply must be low for safe gas exchange in placenta
Diabetes: pregnancy hormones worsen insulin sensitivity and increase risk of macrosomia

38
Q

What is a doppler test?

A

Used for surveillance in blood flow using ultrasound, based on the wave pattern

39
Q

What is an umbilical artery doppler test?

A

Surveillance of resistance foetal blood flow based on wave pattern of blood flow in the umbilical artery. This is important for determining uteroplacental and foetal circulation, useful in DIAGNOSIS of IUGR. It has minimal benefits for screening in low risk populations.

40
Q

Where is the umbilical artery doppler test performed?

A

Typically taken near the insertion site for the placenta or the umbilical cord

41
Q

What are the features of blood flow to foetus in first trimester and beginning of second trimester?

A

Placenta has fewer vessels for maternal blood to supply foetus in early pregnancy so resistance is high, increasing the SDR and reducing EDV

42
Q

How does blood flow to foetus change in pregnancy?

A

As the foetus matures, there is greater diastolic flow and lower placental resistance, causing a drop in the SDR

43
Q

What is normal foetal heart rate?

A

160-200bpm

44
Q

What are the measurements in the umbilical artery doppler test?

A

SDR: systolic to diastolic ratio
EDV: end-diastolic volume
PDV: peak diastolic volume
TAPV: Time averaged peak veolicty

45
Q

What is a normal umbilical artery doppler?

A

During pregnancy, there will be a progressive increase in the diastolic velocity and reduced resistance in the umbilical artery doppler, so decrease in SDR and TAPV

46
Q

What causes increased SDR?

A

Reduced blood flow in diastole
> This occurs due to placental insufficiency

47
Q

What is absent end diastolic flow?

A

Increased placental resistance to diastole results in very low or absent EDV
> This occurs due to placental insufficiency and is an early sign of foetal hypoxia

48
Q

What is reverse diastolic flow?

A

> This occurs due to placental insufficiency where blood flow in diastole is not regulated. This is a late sign of foetal hypoxia, when it is more progressive.

49
Q

What are the results on umbilical artery doppler when abnormal?

A

Change in waveform or measurement ratos.

50
Q

What is intrauterine growth restriction?

A

Intrauterine growth retardation is when the foetal size is below the expected standard for gestational age, typically in the 10th centile where 90% of foetuses of the same gestational age are larger. This is determined by comparing to developmental criteria.

51
Q

What is the pathophysiology of IUGR?

A

Placental insufficiency due to an issue in the remodelling of the spiral arteries to create low-resistance-high flow system.

52
Q

What is the consequences of IUGR?

A

Foetus has lower stores of free fatty acids and glycogen, inducing hypoglycaemia and lower subcutaneous fat.
Low oxygen uptake induces EPO production and leads to foetal polycythaemia, directing blood flow to the vital organs away from the developing liver and bones.
There is reduced foetal kidney function and the volume of amniotic fluid.

53
Q

What is symmetrical IUGR?

A

Head and brain are small along with the rest of the foetal body. This occurs due to issue in early trimester such as infection, genetic disorder or congenital heart disease.

54
Q

What is assymetrical IUGR?

A

Head and brain are expected size but disproportionally smaller body due to later trimester damage.
To compensate organs such as liver, reducing glycogen storage and adipose bodily deposition
This occurs because of vasodilation of vessels supplying vital organs of the heart and brain, leading to foetal kidney failure. This is associated with uteroplacental insufficiency.

55
Q

What is the decidual reaction?

A

Changes in the endometrium in order to prepare for trophoblast invasion preventing it entering myometrium to form the decidua, future maternal side of the placenta. Failure of this to occur in the corpus of the uterus leads to ectopic pregnancy, typically inside the fallopian tubes.

56
Q

What is the corpus of the uterus?

A

Main body of uterus where implantation occurs

57
Q

What are the consequences of sub-optimal decidualisation of endometrium?

A

Placental insufficiency and pre-eclampsia because of limited spiral artery remodelling.

58
Q

What are the maternal risk factors for IUGR?

A

Low BMI, eating disorder, social deprivation
Constitutionally small (short height)
Uterus morphology
Infection with rubella, measles or cytomegalovirus
Chronic disease eg hypertension

59
Q

What is an abnormal uterus morphology?

A

Unicornuate uterus: half uterus forms
Bicornuate uterus: fusion of both uterus
Ashermann syndrome: scar tisse in uterus

60
Q

What are the foetal risk factors for IUGR?

A

Infection with rubella, measles or cytomegalovirus
Genetic abnormalities
Drug teratogen
Foetal abnormalities

61
Q

Which foetal genetic abnormalities cause IUGR?

A

Methylation disorder which impairs regulation of genes in metabolic adaptation.

62
Q

What are the placental risk factors for IUGR?

A

Infection with rubella, measles or cytomegalovirus
Genetic abnormalities
Placental abnormalities such as singular umbilical artery, abruption from uterus or infarction

63
Q

Infection acronym for IUGR?

A

T: TOXOPLASMOSIS
O:
R: RUBELLA
C: CYTOMEGALOVIRUS
H: HERPES
S: SYPHYLLIS

64
Q

Consequences of IUGR in first trimester?

A

Reduced hyperplasia with symmetrical IUGR

65
Q

Consequences of IUGR in 2nd-> 3rd trimester?

A

Reduces hypertrophy so assymetrical IUGR

66
Q

What are the long term consequences of IUGR?

A

Increased risk of metabolic syndrome, type 2 diabetes and cardiovascular disease. This is because foetus adapts to malnutrition and hypoxia by reducing insulin sensitivity which continues in adult life.

67
Q

What is the thrifty gene hypothesis?

A

Evolutionary advantage for individuals who could store more fat in times of famine