EDU 248, chapter 2, 2014sp, causes of ID, CCC

1. Perinatal and Postnatal
Causes of Intellectual
Disabilities
Education of Students with an Intellectual Disability: Research and
Practice; Foreman, Phil; 2009

2. Perinatal Causes
• Perinatal causes of prematurity are the causes that happen right
before and after a baby’s birth. This may be up to 4 weeks after birth
• Prematurity – the main cause of intellectual disability associated with
this time period
• Usually 36 weeks or less gestational period
• May be classified by birth weight
• Extremely Low Birth Weight: < 2.2 pounds (<1000 g)
• Very Low Birth Weight: 2.2 – 3.3 pounds (1000 – 1500g)
• Moderately Low Birth Weight: 3.3 – 5.5 pounds (1500 – 2500g)
• Is the baby’s weight appropriate for gestational age?
• Small for gestational age (below 10th %) – SGA
• Large for gestational age (above 90th %) - LGA

3. Survival Rates
• Survival rates for premature babies have increased; however, that has
led to an increase in the numbers of children with developmental
disabilities
• Ethical debates continue as medical science has evolved
• It is not known whether the premature births are the cause or the
effect of intellectual disabilities in some instances.
• Some developmental delays may not show up in LBW children until
later years
• LBW, low APGAR scores, multiple births and complications in labor
are all risk factors during the perinatal period

4. Other Perinatal Factors
• Some may cause brain damage
• Others may not cause physical or intellectual disabilities, but my
cause later learning disabilities, autism, or attention difficulties
• “At risk” categories are helpful if it leads to provisions for support
with early identification

5. Postnatal Causes of Intellectual
Disabilities
• Head injury –
• Primarily accidents – traumatic brain injury (TBI)
• Shaken baby syndrome – most common form of non-accidental head injury
that affects developing brains
• TBI is one of the most preventable causes of intellectual disabilities
•
•
•
•
Use of helmets
Car seats
Safe playgrounds
Awareness of shaken baby syndrome
• Problems may be temporary, lifelong, or result in death of a child
• Severity of an injury has a direct correlation to the severity of the intellectual
disability or resulting death

6. Postnatal Causes (cont.)
• Infections
• Meningitis – vaccinations have reduced the numbers of disabilities related to
meningitis and related illnesses in developed countries
• Encephalitis – vaccinations have reduced these numbers as well
• Degenerative Disorders
• Rett syndrome – appears primarily in girls who have developed normally for 6
– 18 months; is prenatal, but doesn’t show up until a child is older; high
incidence of autism associated with Rett syndrome
• Seizure Disorders
• More frequent and more severe seizures are associated with intellectual
disabilities than mild epilepsy

7. Postnatal Causes (cont.)
• Toxic-Metabolic Disorders
• Lead poisoning – most likely to happen to children living in poverty or where
lead is still being used in gas and other chemicals; highly preventable cause of
intellectual disabilities
• Malnutrition
• Primarily in countries with chronic malnutrition
• Relatively rare cause of intellectual disabilities
• Environmental Deprivation
• Non-stimulating environments impact intellectual development (think longterm institutional care, Romanian orphanage babies)
• Questions arise about the impact of other risk factors – poverty, poor medical
care, diet, maternal use of drugs and alcohol, environmental toxins, etc.

8. Preventing Intellectual Disabilities
• Preventive and screening tests
• Vaccinations
• Reduction in numbers of children institutionalized has reduced
numbers of secondary disabilities
• Genetic testing and screening tests will continue to raise ethical
questions