Gestational Age and Autism Spectrum Disorder: Trends in Risk Over Time.
The extra autism risk tied to preterm birth has dropped since the 1980s, so early gestation is now a softer warning sign.
01Research in Context
What this study did
Atladóttir et al. (2016) tracked babies born from 1980 to 2009. They asked: does being born early still raise autism risk today?
They compared each birth-year group to see if the preterm-ASD link stayed the same or changed.
What they found
The extra autism risk from preterm birth has shrunk. It is still there, but weaker in kids born after 2000.
In short, early birth matters less now than it did thirty years ago.
How this fits with other research
Khan et al. (2012) and Hwang et al. (2013) already showed preterm kids with ASD have slightly higher symptom scores. The new study extends those snapshots by showing the gap is closing over decades.
Lyall et al. (2012) found gestational diabetes raises autism odds. Ó et al. add that the calendar year also counts: the same week of early birth carries less risk today.
Chiviacowsky et al. (2013) showed 1980s cases would meet today’s broader ASD rules. Together the two papers hint that wider diagnosis, plus better neonatal care, may explain why the preterm signal has faded.
Why it matters
When you read an older file that lists “born at 30 weeks,” do not over-predict autism risk. Update your baseline: the child’s birth year already weakens that old red flag. Use current assessments, not decades-old odds.
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02At a glance
03Original abstract
Autism Spectrum Disorder (ASD) is a serious neurodevelopmental disorder. Several previous studies have identified preterm birth as a risk factor for ASD but none has studied whether the association between gestational age and ASD has changed over time. This is a Danish population-based follow-up study including live-born singletons born in Denmark between 1980 and 2009, identified in the Danish Medical Birth Registry, a study population of 1,775,397 children. We used a Cox regression model combined with spline to study the risk for ASD by gestational age across three decades of birth cohorts. We included 19,020 children diagnosed with ASD. Across all birth year cohorts, we found that the risk of being diagnosed with ASD increased with lower gestational age (P-value: <0.01). Across all gestational weeks, we found a statistically significant higher risk estimates in birth cohort 1980 to 1989, compared to birth cohorts 1990 to 1999 and 2000 to 2009, respectively. No statistically significant difference in risk estimates was observed between birth cohort 1990 to 1999 and 2000 to 2009. The observed time trend in risk of ASD after preterm birth may reflect: (1) a change in the risk profile of persons with ASD due to the broadening of ASD diagnostic criteria over time; or (2) improved neonatal care for low GA infants, which has reduced risk of adverse outcomes like ASD in preterm children.
Autism research : official journal of the International Society for Autism Research, 2016 · doi:10.1002/aur.1525