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reproduction, development and ageing > 2. Fetal growth and abnormalities of human development > Flashcards

2. Fetal growth and abnormalities of human development Flashcards

1
Q

How does foetal growth change through pregnancy?

A

Period of acceleration of growth, followed off by plateauing at the end

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2
Q

How does foetal weight change through pregnancy?

A

Gradually increases at start, but the majority occurs in the second half of pregnancy

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3
Q

Why may it not be useful to use data for foetal growth and weight from failed pregnancies?

A

One of the causes of miscarriage is foetal growth restriction - there will be large amounts of inaccuracies

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4
Q

When is the majority of organogenesis completed?

A

Week 12

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5
Q

What can an interruption in placental development in the early and late stages cause?

A

Early - early onset foetal growth restriction

Late - reduced foetal weight gain

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6
Q

What 2 components does foetal growth depend on?

A
  • Genetic potential (mediated through growth factors) e.g. if both parents are tall
  • Substrate supply - derived from placenta, dependent on uterine and placental vascularity
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7
Q

What 3 phases characterise normal foetal growth (in terms of cells)?

A

1) Cellular hyperplasia - increased cell division, 4-20 weeks
2) Hyperplasia and hypertrophy - increased cell size, 20-28 weeks
3) Hypertrophy - also accumulation of muscle, fat and connective tissue, last trimester

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8
Q

In which trimester does the vast majority of growth take place?

A

3rd trimester (but tailing off of foetal growth velocity at 34 weeks)

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9
Q

How does the maternal store of adipose and glucose change?

A

Increases vastly (after 20-week mark)

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10
Q

How can foetal size be assessed ante-natally?

A

• Palpating the abdomen
• Measure the uterus
- tape measure technique - symphysis fundal height
- distance over the abdominal wall from the symphysis to the top of the uterus
• Ultrasound

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11
Q

How does the symphysis fundal height change with time?

A

Correlates with the number of weeks, but gains more variability closer to term

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12
Q

Why might a baby be measured as smaller than usual?

A
  • Wrong dates
  • Small for gestational age
  • Oligohydramnios (less fluid)
  • Transverse lie
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13
Q

Why might a baby be measure as larger than usual

A
  • Wrong dates
  • Large for gestational age
  • Polyhydramnios
  • Molar pregnancy
  • Multiple gestation
  • Maternal obesity
  • Fibroids
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14
Q

What are the pros and cons of symphysis fundal height?

A

Pros
• Simple and inexpensive

Cons
• Low detection rate
• Great inter-operator variability
• Influenced by a number of factors

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15
Q

How can you date the pregnancy?

A
  • Ask the mother for the first day of her last menstrual cycle (inaccurate e.g. abnormal bleeding)
  • Better to use the crown rump length (CRL) - except in IVF, as we know when the embryos were made
  • Use head circumference after 14 weeks, as CRL becomes inaccurate
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16
Q

What 4 biometrical parameters are combined to give the estimated foetal weight (EFW), to assess foetal growth?

A
  • Bi-parietal diameter (BPD) - distance between the two sides of the head
  • Head circumference (HC)
  • Abdominal circumference (AC)
  • Femur length (FC)
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17
Q

What maternal factors can influence foetal growth?

A
  • Poverty
  • Age
  • Drug use
  • Weight
  • Disease
  • Smoking
  • Alcohol
  • Prenatal depression
  • Environmental toxins
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18
Q

What foeto-placental factors can influence foetal growth?

A
  • Genotype
  • Gender
  • Hormones
  • Previous pregnancy (previous intra-uterine growth restriction can increase risk in next pregnancy)
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19
Q

Does prolactin affect pregnancy?

A

No

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20
Q

Does insulin affect pregnancy?

A

Yes - controls the cell number (direct mitogenic affect, influencing glucose uptake and consumption)

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21
Q

Do iodothyronines affect pregnancy?

A

Probably by third trimester

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22
Q

What 3 principles does the customised standard define individual foetal growth potential by?

A
  • Adjusted to reflect maternal constitutional variation
  • Free from pathological factors
  • Based on foetal weight curves derived from normal pregnancies
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23
Q

What is macrosomia?

A

Abnormality that is larger than usual

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24
Q

What is neonatal hydrocephalus?

A

Baby has a very large head, with extra fluid in the brain

25
Q

What is achondroplasia?

A

Child has a normal trunk, but short limbs

26
Q

What is the most sensitive and specific centile?

A
  • Sensitive (false positives) - 10th

* Specific (false negatives) - 3rd

27
Q

Why is the 10th centile sensitive (false positives)?

A
  • Will capture all babies with foetal growth restriction

* But this also includes babies that are just small for GA

28
Q

Why is the 3rd centile specific (false negatives)?

A

All babies in the 3rd centile will have foetal growth restriction, but some may be missed

29
Q

What is the definition for small for gestational age?

A

Estimated birth weight that is <10th centile

30
Q

What is the most common factor identified in stillborn babies?

A

Intrauterine growth restriction

can be avoided if we time the delivery better

31
Q

What are the short term problems of LBW/FGR/pre-maturity?

A
  • Respiratory distress
  • Intraventricular haemorrhage (bleeding in brain) - risk of cerebral palsy
  • Sepsis - due to immature immune system
  • Hypoglycaemia - undeveloped liver
  • Necrotising enterocolitis - diversion of blood to other places
  • Jaundice
  • Electrolyte imbalance
32
Q

What are the medium term problems with LBW/FGR/pre-maturity?

A
  • Respiratory problems
  • Developmental delay
  • Special-needs schooling
33
Q

What are the long term problems with LBW/FGR/pre-maturity?

A
  • Ischaemic heart disease
  • Congenital heart diseases
  • Diabetes
34
Q

What are the causes of small gestational age?

A
  • Placental insufficiency (20%)
  • Foetal problem (5%) e.g. chromosome abnormality, congenital infection

(Most are normal and not dated properly)

35
Q

When is the period of placentation?

A

10-12 weeks

36
Q

What are trophoblasts?

A
  • Cells forming the outer layer of a blastocyst
  • Provide nutrients to the embryo and develop into a large part of the placenta
  • Invade the placenta, to get rid of the muscular wall
  • Same molecular mechanisms as tumours, but are highly controlled
37
Q

What is the placenta?

A
  • Special endocrine organ (produces peptide and steroid hormones)
  • Functions as a transient hypothalamo-pituitary-gonadal axis
  • Responsible for exchange of nutrients, gases and waste
  • Maintains immunological distance
38
Q

How does the placenta look like in a non-pregnant woman compared to a pregnant woman?

A
  • Non-pregnant - spiral arteries sit within the endometrium

* Pregnant - spiral arteries open up (trophoblasts form a funnel shape)

39
Q

What happens to the placenta in pre-ecamptic toxaemia (PET)?

A
  • Trophoblastic invasion has failed
  • Spiral arteries remain thick and narrow
  • Ischaemic changes and endothelial imbalance - less blood to the baby
40
Q

What 3 things define pre-eclampsia in a pregnant woman?

A
  • Hypertension (on 2 separate occasions)
  • Oedema
  • Proteinuria (over 24 hours)
41
Q

What is foetal growth restriction without pre-eclampsia called?

A

Foetal syndrome

42
Q

What kind of babies is pre-eclamptic toxaemia associated with?

A

Small babies

43
Q

When does pre-eclampsia usually occur?

A

After the 20th week of gestation

44
Q

What obstetric history factors signal for current foetus monitoring?

A
  • Maternal HT
  • FGR
  • Stillbirth
  • Placental abruption
45
Q

What is screened for in ‘at risk’ pregnancies at 24 weeks?

A
  • PAPP=A < 0.4 MoM - Down’s syndrome
  • Maternal systemic disease e.g. HT
  • Uterine artery Doppler ultrasound (check for higher resistance flow)
46
Q

What happens to the amniotic fluid if the placenta fails?

A
  • Higher resistance in umbilical artery
  • Baby stops growing - reduction in foetal movements
  • Blood diverted to vital organs
  • Less blood to kidneys
  • Less urine contribution to amniotic fluid
  • Less amniotic fluid

Baby needs to be taken out to prevent intrauterine death

47
Q

When does increased impedance in the umbilical arteries become evident?

A

When at least 60% of the placental vascular bed is obliterated

48
Q

What is the umbilical vein?

A

Vein that carries oxygenated blood from the placenta to the foetus

49
Q

Where does 25% of blood flow from the umbilical vein go to?

A

Ductus venosus (shunts flow to the inferior vena cava, bypassing the liver so more blood goes to the brain)

50
Q

Why is foetal movement important?

A
  • Reduction in movements may priced foetal death by a day or more
  • Counting may be of value in assessing foetal wellbeing
51
Q

What is the most commonly used method to measure foetal movements?

A

Cardiff kick chart

52
Q

What medication should be administered at gestation <36 weeks if there is FGR?

A

Corticosteroids

53
Q

How can intra-uterine growth restriction (IUGR) be defined into 2 categories?

A

Early IUGR
• Low incidence
• Correlated to maternal disease e.g. pre-eclampsia
• Difficult to manage

Late IUGR
• More common
• Rarely correlated to pre-eclampsia
• Easy to manage

54
Q

What are the symptoms of pre-eclampsia?

A
  • Blurred vision
  • Headache
  • Swelling in hands and feet
55
Q

What are the risk factors for pre-eclampsia?

A
  • Previous history
  • Multiple gestations
  • Hypertension, diabetes, kidney disease
56
Q

What are the risks for the foetus in pre-eclampsia?

A
  • Stillbirth
  • FGR
  • Pre-term delivery
57
Q

How do you deal with FGR?

A
  • Monitor foetus and mother
  • Try deliver after 28 weeks, but deliver early if needed
  • Corticosteroids if less than 36 weeks
58
Q

What is the long term maternal consequences for pre-eclampsia?

A
  • Stroke

* Cardiovascular disease

reproduction, development and ageing (7 decks)

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