Fetal Growth and Nutrition Flashcards
What is the most important factor in fetal growth?
Substrate supply via the placenta
What is the primary cause of growth restriction?
Poor placentation
Infant mortality and morbidity is lowest at ___ wks
39-40
• Low birthweight (LBW) ____g
• Low birthweight (LBW) <2500g
• Very low birthweight (VLBW) <1500g
• Extremely low birthweight (ELBW) <1000g
Macrosomia > 4500g
• Small for gestational age (SGA) __th centile
• Small for gestational age (SGA) <10th centile
Large for gestational age (LGA) >90th centile
What are the four types of birthweight centiles?
- Population reference
- Population standard
- Fetal growth curves
- Customised birthweight
When is your metabolic capacity determined?
In fetal life and infancy
What are the three most important determinants of fetal growth?
- Nutrition
- Hormones
- Genetics
What are the four components of the fetal diet in utero?
- Glucose
- Amino acids
- Lactate
- Fatty acids
What is the most important hormone in fetal growth?
Insulin-like growth factors
What is the role of IGFRs in fetal growth?
- Mitogens
- Protein anabolism,
- Paracrine and endocrine hormones
What is the difference in function between IGF2 and IGFR in fetal growth?
- IGF1 regulated by fetal nutrition
- IGF2 main circulating fetal IGF, constitutive drive for growth
What is the role of insulin in fetal growth?
- Regulate growth when nutrition is plentiful
- Increases glucose uptake, fat deposition, protein anabolism, placental growth
- Amino acids stimulate fetal insulin secretion in early pregnancy
Why does deficiency of growth hormone have minimal effects on fetal weight despite high circulating concentrations?
Absence of receptorss in the liver
What is the role of corticosteroids in fetal growth?
- Promote differentiation and tissue maturation
- Decreased DNA synthesis and cell division
Which enzyme is the placental barrier to maternal cortisol?
11 betaHSD2
Fetal growth normally limited by ____
Constraint
Which factors cause maternal constraint?
- Ability of utero-placental unit to supply oxygen and nutrients
- Maternal size
- Maternal age
- Parity
- Shorter inter pregnancy interval
- Macronutrient imbalance
Which factors cause constraint during embryogenesis?
- Twins
- Periconceptual undernutrition
Compare fetal and postnatal growth
- Constraint
- Growth regulation
- Maternal environment vs genetic potential
- Endocrine status adequate -> regulation by substrate supply
VS nutritional status adequate -> regulation by endocrine status
Define fetal growth restriction
- In utero growth potential limited by pathological process
- Causes decreased accretion of fat and lean tissue +/- skeletal growth
Which fetal pathologies can lead to fetal growth restriction?
- Congenital malformation
- Congenital infction
- Toxins
- Chromosomal disorders
- Specific genetic disorders
What is the genetic abnormality in Beckwith Wiedemann Syndrome? How does this affect fetal growht?
- Overexpression of IGF2 (maternal allele normally imprinted)
- Usually due to paternal uniparental disomy
- Causes macrosomia
What is the genetic abnormality in Russell Silver Syndrome? How does this affect fetal growht?
- 60% due to reduced expression of IGF2
- SGA, short, normal head growth
What are the health risks associated with the thrifty phenotype?
- Low nephron mass
- Low lean mass
- Endothelial dysfunction, arterial stiffness
- Insulin resistance
- Dyslipidaemia, central adiposity
- Exaggerated stress
What is the mechanism of gestational diabetes?
• Excess fetal substrate (glucose, FFA) -> excess fetal insulin
Excess substrate + excess insulin -> excess growth
