Normal and disordered fetal growth Flashcards
What are the types of growth restriction?
Small for gestational age (SGA)
Intrauterine growth restriction (IUGR)
Low birth weight (LBW)
What is SGA?
fetus less that 10th percentile for age (weeks)
What is IUGR?
Fetus unable to reach genetically predetermined size
What is LBW?
birth weight less that 2500g (SGA or premat)
What are the classifications of SGA?
- Normal small fetus - no risk
- Abnormal small fetus - chr or struc abnorm
- GR fetus - placental dysfunction - need treating
How many SGA babies are at risk of perinatal death?
40%
What is symmetrical FGR?
Head and body are in proportion
Nutritional insult early in development
What is asymm FGR?
Abnormal liver to brain ratio (greater than 6)
Nutritional insult later in development so the brain is spared and other organs are affected
What are fetal factors contributing to IUGR?
Chr aberrations, congenital structural defects and genetics
RISK FACTORS - infections, multiples, malformations
Maternal factors in IUGR
Chronic disease e.g. hypertension, pre-eclampsia, malnutrition, infection
RISK FACTORS - drugs
Placental factors in IUGR
Defective placenta, decreased functioning mass
Underlying mechanisms of IUGR
Insuff gas exchange and nutrient delivery
decrease O2 carrying capacity in the mother
Maternal diet plays a role
Nutritional insult can cause epigenetic changes
What does the placenta transport?
Gases
Nutrients - glucose (hexose transporter), aa (active TP), IgG, unconj bilirubin
Drugs
Infections
Perinatal implications of IUGR
Increased fetal morbidity and mortality Still birth Prematurity Asphyxia Congenital malformation
What is the thrifty hypothesis?
Metabolic deprived fetus is metabolically programmed for insulin resistant and impaired glucose metabolism therefor is predisposed to a range of health risks
How is IUGR managed?
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
How is IUGR prevented?
Can't really be prevented Some benefit shown from: - LDA and miniheparin - Decreased maternal smoking - ABs to prevent/rx UTIs - Antimalarial prophylaxis
What is the overall management of IUGR?
Surveillance until risk of in utero demise is greater than the risk of delivery and prematurity
What is fetal macrosomia?
BW greater than 4000g
What is the prevalence of macrosomia?
9-10% of neonates 4000g (different in different countries - genetic and enviro factors)
1.5% 4500g
What are the risk factors for macrosomia?
Maternal hyperglycemia, previous macro infant, pre-preg obesity, male fetus, post-term gestation, parental height/race, mother older than 20
What are the problems with macrosomia?
Morbidity and mortality
Maternal diabetes
Birth trauma - shoulder dystocia
Neonatal hypoglycemia
