Small increase in risk of autism seen for pre- and post-term births
Risk is low no matter the timing of birth, but new insights could improve understanding of ASD

Date:
September 22, 2020
Source:
PLOS
Summary:
A study of more than 3.5 million Nordic children suggests that
the risk of autism spectrum disorder (ASD) may increase slightly
for each week a child is born before or after 40 weeks of gestation.



FULL STORY ==========================================================================
A study of more than 3.5 million Nordic children suggests that the risk
of autism spectrum disorder (ASD) may increase slightly for each week a
child is born before or after 40 weeks of gestation. Martina Persson of
the Karolinska Institutet in Stockholm, Sweden and colleagues present
these findings in the open-access journal PLOS Medicine.


==========================================================================
The causes of ASD are complex and remain unresolved, but they likely
involve both genetic and environmental factors. Some previous research
suggests that children born before or after their due dates (40 weeks
of gestation) may have an elevated risk of ASD. However, most of those
studies have been limited in scope and have not accounted for sex and
birth weight.

To better understand potential links between gestational age and risk of
ASD, Persson and colleagues analyzed medical registry data on more than
3.5 million children born in Sweden, Finland, or Norway between 1995 to
2015. Within that cohort, 1.44 percent of the children were diagnosed with
ASD, and 4.7 percent were born pre-term -- before 37 weeks of gestation.

The analysis, which covered gestational ages at birth ranging
from 22 to 44 weeks, showed that overall risk of ASD was low for
every age, especially for girls born post-term (after 42 weeks of
gestation). However, the relative risk of ASD increased for each week
of gestational age below or above 40 weeks.

Of the children born at term -- in weeks 37 to 42 -- 0.83 percent were diagnosed with ASD. The percentage was 1.67 for those born in weeks
22 to 31, 1.08 percent for weeks 32 to 36, and 1.74 for weeks 43 to
44. These differences in risk were independent of sex and birth weight
for gestational age.

These findings provide new insights into the potential links between
risk of ASD and gestational age at birth -- which is potentially
modifiable. More research will be needed to clarify these links and
investigate whether they could lead to strategies to lower risk by
addressing pre-term birth.


========================================================================== Story Source: Materials provided by PLOS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Martina Persson, Signe Opdahl, Kari Risnes, Raz Gross, Eero
Kajantie,
Abraham Reichenberg, Mika Gissler, Sven Sandin. Gestational age
and the risk of autism spectrum disorder in Sweden, Finland,
and Norway: A cohort study. PLOS Medicine, Sept. 22, 2020; DOI:
10.1371/journal.pmed.1003207 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200922144319.htm

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