Normal and disordered fetal growth

Question 1

What are the types of growth restriction?

Answer 1

Small for gestational age (SGA)
Intrauterine growth restriction (IUGR)
Low birth weight (LBW)

Question 2

What is SGA?

Answer 2

fetus less that 10th percentile for age (weeks)

Question 3

What is IUGR?

Answer 3

Fetus unable to reach genetically predetermined size

Question 4

What is LBW?

Answer 4

birth weight less that 2500g (SGA or premat)

Question 5

What are the classifications of SGA?

Answer 5

1. Normal small fetus - no risk
2. Abnormal small fetus - chr or struc abnorm
3. GR fetus - placental dysfunction - need treating

Question 6

How many SGA babies are at risk of perinatal death?

Answer 6

40%

Question 7

What is symmetrical FGR?

Answer 7

Head and body are in proportion

Nutritional insult early in development

Question 8

What is asymm FGR?

Answer 8

Abnormal liver to brain ratio (greater than 6)

Nutritional insult later in development so the brain is spared and other organs are affected

Question 9

What are fetal factors contributing to IUGR?

Answer 9

Chr aberrations, congenital structural defects and genetics

RISK FACTORS - infections, multiples, malformations

Question 10

Maternal factors in IUGR

Answer 10

Chronic disease e.g. hypertension, pre-eclampsia, malnutrition, infection
RISK FACTORS - drugs

Question 11

Placental factors in IUGR

Answer 11

Defective placenta, decreased functioning mass

Question 12

Underlying mechanisms of IUGR

Answer 12

Insuff gas exchange and nutrient delivery
decrease O2 carrying capacity in the mother
Maternal diet plays a role
Nutritional insult can cause epigenetic changes

Question 13

What does the placenta transport?

Answer 13

Gases
Nutrients - glucose (hexose transporter), aa (active TP), IgG, unconj bilirubin
Drugs
Infections

Question 14

Perinatal implications of IUGR

Answer 14

Increased fetal morbidity and mortality 
Still birth 
Prematurity 
Asphyxia
Congenital malformation

Question 15

What is the thrifty hypothesis?

Answer 15

Metabolic deprived fetus is metabolically programmed for insulin resistant and impaired glucose metabolism therefor is predisposed to a range of health risks

Question 16

How is IUGR managed?

Answer 16

Diagnosis - SFH and ultrasound (fetal biometry)
Surveillance - scans and doppler (important for indicating time of delivery before 32 weeks)
Invasive tests - fetal karyotyping, fetal blood sampling and amniocentesis
Neonatal diagnosis - low ponderal index, decreased subcut fat, hypoglycemia, necrotising enterocolitis hyperbilirubinaemia

Question 17

How is IUGR prevented?

Answer 17

Can't really be prevented
Some benefit shown from:
- LDA and miniheparin
- Decreased maternal smoking 
- ABs to prevent/rx UTIs
- Antimalarial prophylaxis

Question 18

What is the overall management of IUGR?

Answer 18

Surveillance until risk of in utero demise is greater than the risk of delivery and prematurity

Question 19

What is fetal macrosomia?

Answer 19

BW greater than 4000g

Question 20

What is the prevalence of macrosomia?

Answer 20

9-10% of neonates 4000g (different in different countries - genetic and enviro factors)
1.5% 4500g

Question 21

What are the risk factors for macrosomia?

Answer 21

Maternal hyperglycemia, previous macro infant, pre-preg obesity, male fetus, post-term gestation, parental height/race, mother older than 20

Question 22

What are the problems with macrosomia?

Answer 22

Morbidity and mortality
Maternal diabetes
Birth trauma - shoulder dystocia
Neonatal hypoglycemia