Infants who are born prematurely (preterm) are known to be at a higher risk of developing certain physical and cognitive disorders. Autism Spectrum Disorder (ASD) is one of the disorders that is common among preterm infants. Now, researchers are investigating whether ASD can be predicted in preterm infants using developmental trajectory scales.
Autism Spectrum Disorder and Preterm Infants
Preterm refers to a woman who goes into labor before 37 weeks of pregnancy. Infants who are born after 24 weeks are often able to survive, but they are vulnerable to a variety of medical and cognitive disorders.
Researchers estimate that seven percent of preterm infants develop ASD, as compared to 1.8 percent of the general population. ASD is associated with a variety of prenatal, neonatal and perinatal risk factors. Some of these factors include:
- Maternal health
- Maternal medication use
- Neonatal risks:
- Low birth weight
- Perinatal risks:
- Low gestational age
- Low birth weight
- Acute/chronic lung disease
These are just some examples of the risk factors associated with preterm labor and ASD. There are a variety of factors that may factor into the individual health of a mother and child.
Can Autism Spectrum Disorder be Predicted in Preterm Infants?
New research published in the journal Pediatrics offers promising data about preterm infants and the risk of developing ASD. Researchers tested 319 preterm children using the Bayley Scales of Infant Development. The examinations were done at six, 12 and 24 months. The examinations were done using group-based trajectory modeling,
“to assess whether early-life developmental trajectory predicted autism at 5 years of age.”
Developmental trajectory has been used previously to assess high-risk populations, such as infants who have siblings with ASD, or infants who have genetic disorders. This particular research, however, is the first that offers prospectively obtained data.
According to the data, a small percentage of infants who are born preterm and develop ASD have a similar early-life trajectory to children born at term. These infants have a decline in mental development between 12 and 24 months. The highest-risk group, however, had low cognitive scores at six months, with cognitive decline present over time. This allows for early identification and intervention.
Data also shows that infants who have low cognitive scores but who improve by 85 percent, as well as infants with stable cognitive scores, are at a lower risk of developing ASD. This offers some hope for families of preterm infants who may be concerned about their child’s ongoing development.
Risk Factors for Autism Spectrum Disorder
In addition to studying whether developmental trajectory could predict the development of ASD, researchers also studied the risk factors for ASD in preterm infants. In their study, researchers compared 29 children with ASD to 290 children without. The study included nonmodifiable risk factors and modifiable risk factors.
Nonmodifiable risk factors:
- Gestational age
- Birth weight
- Male sex
Modifiable risk factors:
- Chronic lung disease
- Duration of oxygen therapy
Studying these factors has limitations, as the authors note that there was a lack of neuroimaging data available. Therefore, researchers note,
“it is unknown whether there was a contribution of identifiable brain injury to the development of ASD in their subjects. It is likely that at least some of the infants in the low cognitive score group had easily detected brain injury, such as large cerebellar injury or cerebral injury and/or impaired brain development, both of which are associated with low IQ and are suspected to increase the risk of ASD.”
The study also did not include genetic risk factors, which could exacerbate risk factors like premature birth.
The study does confirm some risk factors, however, which could be important in helping families understand the risk and possible predict development of ASD. For example, certain genes are linked to ASD. Children who carry these genes could be more likely to develop ASD in the future.
Also, male sex continues to be strong risk factor regardless of gestational age at birth, but particularly in preterm infants. Researchers believe that male sex may contribute to genetic risks related to sex, as well as an increased vulnerability to certain complications of preterm birth.
Putting the Pieces Together for Parents
What does this research mean for parents? Primarily, it provides an opportunity for healthcare providers to begin intervention as soon as possible. Early intervention for cognitive developmental disabilities, including ASD, is an important key to helping infants and children develop and gain independence.
By identifying certain risk factors, healthcare providers can better target infants who are at the highest risk, and offer reassurance to parents of infants who are at a low risk. Research recommends that healthcare providers identify high-risk infants with low cognitive scores at six months, as well as those whose scores are declining over time. This can help target interventions and mitigate further development of ASD-related symptoms.
Most importantly, research recommends that healthcare providers work to identify these high-risk infants by discharge from the hospital, or at least by six months of age. The earlier interventions begin, the better the outcome will be for the infant.