(RxWiki News) Being born early or late already carries some health risks for both mothers and their newborns. Now there's evidence an early or late birth can worsen symptoms of children with autism.
A new study reveals that preemies and late arriving babies who go on to develop autism are at a higher risk for self-inflicted injuries than autistic children born at term.
"Attend all prenatal appointments with your caregiver."
Tammy Movsas, of the Department of Epidemiology at Michigan State University, led a study that looked for patterns in the symptoms of autistic children born before 37 weeks or after 42 weeks of pregnancy.
Using 2006-2010 data from the Kennedy Krieger Institute at Johns Hopkins University, Movsas analyzed the records of 4,188 women whose autistic children ranged from age 4 to age 21.
She grouped the children according to when they were born: very preterm (before 34 weeks), preterm (34-37 weeks), on time (37-42 weeks), and post-term (after 42 weeks).
Each mother filled out questionnaires about their children's symptoms, including questions about social awareness, social cognition, social communication, social motivation and autistic mannerisms.
The two assessments used included the 40-item Social Communication Questionnaire (SCQ) and the 65-item Social Responsiveness Scale (SRS). A score of 15 or higher on the SCQ suggests a child has an autism spectrum disorder.
The SRS assesses people on a continuum: under 55 means the child is not autistic or is borderline, a score between 55 and 75 means they have mild to moderate symptoms, and a score over 75 suggests severe symptoms of autism.
The scores for symptoms of autism spectrum disorder were greater among children who had been preemies or late arrivals. The average screening scores of symptoms for children born on time was 22.6 and 85.6 on the two standard assessments used to measure the kids' autism symptoms.
Those children born very early scored 24.5 and 90, and those born one to three weeks early scored 23.7 and 88.1. Average scores of babies who had been born late were 25.5 and 88.4.
Although the study did not find any difference in motor skill development among the four groups, it did find a delay in children's ages when they first walked and first talked for children born before 34 weeks.
The researchers' calculations took into account each child's gender, ability to talk, IQ score and growth rate while in their mother's womb.
Although Movsas found that the length of a woman's pregnancy plays a part in how severe the condition is for children who develop autism, she did not find a reason for this link.
One possibility is that whatever reason led to the child's lengthened or shortened time in the womb in the first place is also leading to an increase in the autism symptoms.
In other words, it's not the early or late birth that's likely causing the more severe symptoms. Instead, whatever hidden condition caused the baby to arrive early or late may also be contributing to how severe the child's condition is.
One way to think about it is that children born on time - even if they go on to develop autism - are less likely to show as severe symptoms.
"The outside environment in which a preterm baby continues to mature is very different than the environment that the baby would have experienced in uteri," Movsas said. "This change in environment may be part of the reason why there is a difference in autistic severity in this set of infants."
For example, a baby is exposed to more hormones the longer he or she lives in the womb, which may or may not be related to how their symptoms show themselves later.
A longer pregnancy also increases the chances that a mother will experience complications with her placenta and/or that she will need a C-section or a birth requiring assistance from a vacuum or other medical device, Movsas said.
The study appeared online in April in the Journal of Autism and Development Disorders. The research was funded by the National Institutes for Health. No conflicts of interest were noted.