Small for Gestational Age Flashcards
What is small for gestational age (SGA)?
Small for gestational age (SGA) is defined as a fetus that measures below the 10th centile for their gestational age.
What measurements on USS determine fetal size?
Two measurements on ultrasound are used to assess the fetal size:
- Estimated fetal weight (EFW)
- Fetal abdominal circumference (AC)
What is severe SGA?
Severe SGA is when the fetus is below the 3rd centile for their gestational age.
What is low birth weight?
Low birth weight is defined as a birth weight of less than 2500g.
What factors are taken into consideration when using customised growth charts?
Customised growth charts are used to assess the size of the fetus, based on the mother’s:
- Ethnic group
- Weight
- Height
- Parity
What causes SGA?
The causes of SGA can be divided into two categories:
- Constitutionally small, matching the mother and others in the family and growing appropriately on the growth chart
- Fetal growth restriction (FGR)
- Also known as intrauterine growth restriction (IUGR)
What is fetal growth restriction (FGR)?
Fetal growth restriction (FGR), also known as intrauterine growth restriction (IUGR), is when there is a small fetus (or a fetus that is not growing as expected) due to a pathology reducing the amount of nutrients and oxygen being delivered to the fetus through the placenta.
Briefly differentiate between small for gestational age (SGA) and fetal growth restriction (FGR)
Small for gestational age simply means that the baby is small for the dates, without stating why. The fetus may be constitutionally small, growing appropriately, and not at increased risk of complications. Alternatively, the fetus may be small for gestational age due to pathology (i.e. FGR), with a higher risk of morbidity and mortality.
What are the causes of FGR?
The causes of fetal growth restriction can be divided into two categories:
- Placenta mediated growth restriction
- Non-placenta mediated growth restriction, where the baby is small due to a genetic or structural abnormality
Give examples of causes of placenta mediated growth restriction
Placenta mediated growth restriction refers to conditions that affect the transfer of nutrients across the placenta:
- Idiopathic
- Pre-eclampsia
- Maternal smoking
- Maternal alcohol
- Anaemia
- Malnutrition
- Infection
- Maternal health conditions
Give examples of causes of non-placenta medicated growth restriction
Non-placenta medicated growth restriction refers to pathology of the fetus, such as:
- Genetic abnormalities
- Structural abnormalities
- Fetal infection
- Errors of metabolism
What signs would differentiate SGA and FGR?
There may be other signs that would indicate FGR other than the fetus being SGA such as:
- Reduced amniotic fluid volume
- Abnormal Doppler studies
- Reduced fetal movements
- Abnormal CTGs
What are the short term complications of fetal growth restriction?
Short term complications of fetal growth restriction include:
- Fetal death or stillbirth
- Birth asphyxia
- Neonatal hypothermia
- Neonatal hypoglycaemia
What are the long term complciations of fetal growth restriction?
Growth restricted babies have a long term increased risk of:
- Cardiovascular disease, particularly hypertension
- Type 2 diabetes
- Obesity
- Mood and behavioural problems
What are the risk factors of SGA?
There are a long list of risk factors for SGA:
- Previous SGA baby
- Obesity
- Smoking
- Diabetes
- Existing hypertension
- Pre-eclampsia
- Older mother (over 35 years)
- Multiple pregnancy
- Low pregnancy‑associated plasma protein‑A (PAPPA)
- Antepartum haemorrhage
- Antiphospholipid syndrome