IUGR

Question 1

Define small for gestational age (SGA)?

Answer 1

SGA is when a child that is smaller in size than normal for the baby’s sex and gestational age. It is commonly defined as those below the 10th centile.

Severe SGA is defined as below the 3rd gentile.

SGA can be categorised as:

• Normal, babies that have been small on all there scans and are constitutionally small, with growth appropriate to mother’s size and ethnicity.
• Those that have been growth restricted aka IUGR.

Question 2

Define Intrautrerine growth restriction?

Answer 2

Intrauterine growth restriction (IUGR) is a condition where a baby’s growth slows or ceases when it is in the uterus.

They tend to be SGA also however they do not have to be (aka baby who has the genetic potential to be very large but due to IUGR is relatively small still may be above the 10th gentile therefore not IUGR)

Question 3

What are the maternal causes of IUGR? (3)

Answer 3

Maternal:
• Increased maternal age
• Chronic disease (HTN/diabetes/CHF/CKD/absorptive diseases)
• Drug abuse (smoking/alcohol/medication*)

*warfarin, steroids and phenytoin

Question 4

What are the placental causes of IUGR? (3)

Answer 4

Placental causes:
• Pre-eclampsia
• A small placenta that cannot supply the needed nutrients
• Cell death of the placenta

Question 5

What are the fetal causes of IUGR? (4)

Answer 5

Fetal causes:
• Multiple pregnancy (15-20% of twins)
• Chromosomal abnormalities i.e. Down syndrome, Edwards’
syndrome, Turner syndrome or Patau’s syndrome
• Congenital defects – associated with SGA
• Intrauterine infection i.e. CMV, toxoplasmosis, rubella or syphilis

Question 6

What are meant by the terms symmetrical and asymmetrical growth restrictions?

Answer 6

In symmetrical growth restriction there is a global growth restriction so the baby will have normal proportioned head to body. This is suggestive of the growth restriction occurring from early pregnancy.

Asymmetrical growth restriction is when weight followed by length are restricted but the head circumference is not affected. This is suggestive of the growth restriction happening later on in pregnancy. Note there will be an increased brain to liver ratio.

Question 7

What are the causes of symmetrical IUGR? (3)

Answer 7

Tend to occur in an earlier gestation:

• Chromosomal abnormalities (trisomy 13 aka patau, 18,21)
• TORCH infections
• Drugs (nicotine, alcohol, heroin)

Tend to have a severe neurological sequela.

Question 8

What are the causes of asymmetrical IUGR? (4)

Answer 8

Tend to occur in later pregnancy:

• Placental insufficiency
• Pre-eclampsia
• Genetic disorders (Russel-Silver Syndrome)
• Maternal illness

Question 9

What are the short and long term complications of IUGR?

Answer 9

Those with symmetrical IUGR are likely to have a long term neurological sequela and have significant neurodevelopmental delay.

Those who have had less than adequate nutrition in utero tend to feed well postpartum and may achieve an only slightly below normal height and weight.

However studies have shown an infant less than 2.5kg birth weight has an increased risk of CKD, HTN, DM, and thyroid disorders.

Those with congenital and genetic abnormalities will have the associated complications.