Prematurity & Autism
Do we know how long it takes a premature baby to catch up in brain development? Is there anything parents can do to reduce autism risk during this period?
This week’s “Got Questions?” answer comes from two experts affiliated with Autism Speaks. Pediatric neurologist Emily de los Reyes, M.D., (left) specializes in neurodevelopmental disabilities at Nationwide Children’s Hospital, Columbus, Ohio, one of 17 Autism Speaks Autism Treatment Network centers. Psychologist Judith Gardner, Ph.D., (right) supervises the Infant Development Follow-up Program at the Institute for Basic Research in Developmental Disabilities, in Staten Island, New York. Dr. Gardner is the recipient of an Autism Speaks research grant – “Very Early Behavioral Indicators of ASD Risk in Neonatal Intensive Care Unit Infants.”
Dr. de los Reyes: Premature infants generally “catch up” in development by two years of age. You are correct that they are at higher risk for developing neurodevelopmental disabilities. The most common factors predisposing infants to autism include low birth weight, extreme prematurity (before 26 weeks), intrauterine infection during the pregnancy and being a boy. Infants with injuries to the cerebellum (the area of the hindbrain that controls muscle movement) appear to have a particularly high risk of autism.
We advise parents and pediatricians to closely monitor premature infants after discharge. Ideally, these babies have a medical team that includes specialists trained to track the development of premature infants.
Any delays in speech, language or motor development require prompt assessment and referral to an appropriate therapist (speech, occupational, physical, etc.) It’s equally important to monitor for any hearing loss, as this will predispose to language delays. Similarly, your baby’s developmental team should watch for and address any problems with eyesight related to prematurity or disorders of eye alignment.
In addition, you can help foster your premature infant’s development with good nutrition to promote healthy postnatal weight gain. (Talk with your physician and/or an infant nutrition expert for further advice.)
As with all children, early diagnosis of autism provides the opportunity for early intervention that can improve outcomes. Pediatricians can screen for autism as early as the one-year well-baby checkup.
Dr. Gardner: Improvements in medical technology are allowing babies to survive at much earlier gestational ages than ever before. However, many babies born very preterm with extremely low birth weight have associated medical or development problems. These include a higher risk of developing autism. As a result, it's crucial that we conduct further research to deepen our understanding of the long-term effects of preterm birth – including autism risk.
The last trimester is a time of significant growth in a baby's size and weight. However, most crucial brain development occurs in the first and second trimesters. During this early pregnancy period, important brainstem mechanisms form the foundation for subsequent brain development. So far, research indicates that increased risk for autism traces most strongly to what happens during the first and second trimesters.
This doesn't mean that the last trimester is unimportant. We see renewed interest in the health of near-term infants – those born between 35 and 37 weeks of pregnancy. They may be more likely than full-term infants to have certain lung, circulation and feeding problems. For this reason, most obstetricians won't deliver babies early for reasons of "convenience."
As for "catching up," it's helpful to view a preterm baby's development from his or her post-conception age, rather than birth age. Ten weeks after birth, for example, you can expect a baby born at pregnancy week 30 to behave like a full-term newborn. It helps to remember that 10 out of 40 weeks represents a large percentage a newborn’s life (25 percent). By contrast, 10 weeks out of 2 years is a modest 10 percent. This helps explain why we generally don’t see developmental differences at 2 years.
To directly answer your question, my advice would be to treat a preterm baby like any other baby. Talk to the baby. Hold the baby. Love and play with the baby. If your baby is born just a month early or less, try not to worry about rare and unlikely problems.
At the same time, it remains important to monitor the development of any preterm, medically fragile or otherwise at-risk baby. This includes appropriate autism screening and follow-up assessments and, if needed, early intervention services.
Editor’s note: Please also see our Learn the Signs page and our automated Modified Checklist for Autism in Toddlers (M-CHAT) screening tool. Autism Speaks continues to fund a wealth of research into the factors that predispose an infant to autism and into early interventions that can improve outcomes. You can explore these and related studies using this website Grant Search.
Got more questions? Please send them to GotQuestions@autismspeaks.org.