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MBCHB3: Reproduction, Development and Ageing > Lecture 14: Fetal growth > Flashcards

Lecture 14: Fetal growth Flashcards

1
Q

What is low birthweight?

A

<2500g

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2
Q

What is low birthweight associated with?

A
  • x6 fold increase in perinatal mortality and morbidity
  • Increased inattention, hyperactivity and behavioural problems
  • Decreased postnatal growth
  • Lower income
  • Increased adult non-communicable disease i.e metabolic syndrome
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3
Q

What is high birthweight?

A

> 4500g

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4
Q

What is associated with high birthweight?

A
  • Birth trauma
  • Increased neonatal admissions
  • Increased childhood obesity
  • Increased adult non-communicable diseases
  • > Metabolic syndrome
  • > Depends on body composition
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5
Q

What are key risk factors for high birthweight?

A

Maternal obesity and gestational diabetes

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6
Q

How does the environment in early life play into development?

A

Obesinogenic and under-nutrition environment environment can lead to CV disease or metabolic syndrome if theres a mismatch between in-utero environment and external.

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7
Q

What are the determinates of fetal growth?

A
  • Substrate supply (placenta) -> Nutrition
  • Fetal Hormones
  • Genetics
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8
Q

How does the maternal environment constrain growth?

A

Maternal constraint:

  • maternal body habitus (tall v short, fat v slim)
  • Multiple pregnancies
  • First born child
  • Adolescent mother
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9
Q

Describe the fetal supply line:

A

Insert slide 12

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10
Q

How does the placental transport glucose and what is their role?

A

Facilitated diffusion (GLUT 1)

Key oxidative fuel (~80% energy)
Limited fetal gluconeogenesis
Carbon source for tissue accretion

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11
Q

How does the placental transport amino acids and what is their role?

A
  • Active transport
  • Placenta synthesis
  • Fetoplacental shuttle

Key role in metabolic balance between oxidation vs growth

Carbon and nitrogen for tissue accretion, nucleotides (DNA)

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12
Q

What are the fetal growth hormones?

A

IG1, IG2 and Insulin are mjr players

Growth hormones
Thyroid hormones
Corticosteroids
Sex hormones
Placental lactogen
Prolactin
Catecholamines
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13
Q

What regulates IGF1?

A

IGF-1 is regulated by fetal nutrition

AA have little impact, glucose is main substrate in this regulation

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14
Q

What does insulin stimulate in the fetus and how do they act together?

A

Insulin stimulates IGF-1

IGF-1 and insulin act together to match fetal growth to nutrition

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15
Q

What are the actions of insulin in the fetus?

A

Main actions:

  • Tissue accretion
  • Fuel storage
  • > Increases glucose uptake
  • > Fat deposition
  • > Protein anabolism
  • > Placental growth
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16
Q

What is the implication of maternal diabetes?

A

-> Increased glucose crossing the placenta and thus blood glucose of fetus
= Increased substrate and increased fetal insulin
= Excess fetal growth and fuel storage i.e fetal macrosomia

17
Q

How does genetics impact fetal growth?

A
  • Ethnicity and fetal sex account for 20% variance in birthweight
  • Genetic factors have more influence on lean mass
  • Fetal growth is normally limited by constraint
    i. e Non-genetic / non-pathological factors that limit fetal growth
18
Q

What is maternal constraint and how does it impact fetal growth?

A
  • Major constraining factor is the ability of the utero-placental unit to supply oxygen and nutrients
19
Q

What are maternal constraint factors?

A
  • Maternal size (predictor of birth weight)
  • Maternal age - adolescent pregnancy
  • Parity - primiparous
  • Short inter-pregnancy interval
  • Macronutrient imbalance
20
Q

What can causes constraint during embryogenesis?

A
  • Twins even if removed reduces size
  • Periconceptual undernutrition alters fetal growth trajectory

Fetal growth is normally constrained below optimal for survival

21
Q

What determines fetal growth?

A

Fetal growth is normally constrained by the maternal environment

If endocrine status is adequate, growth is normally regulated by substrate supply

22
Q

What determines post natal growth?

A
  • Is normally to genetic potential

- If nutritional status is adequate, growth is normally regulated by endocrine status

23
Q

What is the best birth size terminology?

A

Weight for gestation

Appropriate for gestational age (10-90th centile)
SGA (<10%)
LGA (>90%)

24
Q

What is fetal growth restriction?

A
  • In utero growth potential limited by pathological process
  • Decreased accretion of fat > lean tissue +/- skeletal growth
  • Causes: Fetal undernutrition and fetal pathology
25
Q

What are the causes of fetal undernutrition?

A

Utero-placental dysfunction

  • idiopathic
  • Vascular disease
26
Q

What fetal pathology can cause FGR?

A 
Congenital malformation
Congenital infection
Toxins
Chromosomal disorders
Specific genetic disorders
27
Q

What can cause uteroplacental dysfunction?

A
  • Deficient trophoblast invasion and remodelling of the spiral arteries, with poor development of terminal villi
  • Reduced surface area, diffusion capacity, uteroplacental and fetoplacental blood flow
  • Placental inflammation, hypoxic/hyperoxic stress, antiangiogenic state, thromboexclusive damage
28
Q

What are the consequences of fetal growth restriction in pregnancy and neonatal period?

A

Pregnancy: Preterm birth, asphyxia, still birth

Neonatal period: Asphyxia, Hypoglyceamia, polycythaemia, Death

29
Q

What are the consequences of fetal growth restriction in childhood and adulthood, mother?

A

Childhood: Cerebral palsy, lower IQ, short stature, Obesity

Adulthood: Hypertension, heart disease, CVA

Mother: Ischeamic heart disease

30
Q

What are the potential long term effects on health?

A 
Low nephron mass ->  Hypertension
Low lean mass -> Ischeamic heart disease
Endothelial dysf -> Stroke
Insulin resistance -> Diabetes
Dyslipidemia -> Metabolic syndrome
31
Q

What happens in excess fetal growth?

A
  • Excess substrate
  • > Exaggerated growth potential
  • > Accretion of fat
  • > Macrosomia
32
Q

Write some notes on gestational diabetes:

A
  • Maternal glucose intolerance developing in pregnancy

- Main underlying cause of LGA/macrosomia

33
Q

What is the maternal risk because of excess fetal growth?

A
  • C section
  • Operative delivery
  • Gential tract injuries
  • post partum haemorrhage
  • Inc risk diabetes
34
Q

What is the neonatal risk because of excess fetal growth?

A
  • Shoulder dystocia
  • Brachial plexus injury
  • Birth injury
  • Hyperbilirubinaemia
35
Q

What are the longer term risks of excess fetal growth?

A
  • Childhood obesity
  • Neurological and behavioural problems
  • Adult diabetes / metabolic syndrome
36
Q

Describe the iknock on effects of maternal hormonal imbalance and nutrition changes:

A

Maternal hormonal imbalance and nutrition changes -> Development plasticity/adaptation -> Pancreas, adipose tissue, muscle -> Offspring obesity, metabolic syndrome

  • Cell differentiation
  • Hormone levels
  • Glucose handling
  • Lipid metabolism

All impacted

MBCHB3: Reproduction, Development and Ageing (24 decks)

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