Pregnancy spacing may affect autism risk

By Julie Griffiths on 23 November 2017 Birth spacing Autism

The time between pregnancies may affect the risk of autism, research has found.

A paper published in the journal Autism Research said there was a link between the amount of time between pregnancies and autism spectrum disorder (ASD) in children.  

It found that ASD was increased in second and later-born children who were conceived less than 18 months or 60 or more months after the mother’s previous birth. Other developmental disabilities were not associated with birth spacing.

Using data from the Study to Explore Early Development (SEED), a large six-site case-control study specifically designed to assess pre-conception and prenatal ASD risk factors, the researchers conducted a comprehensive analysis of the association between inter-pregnancy interval (IPI) and ASD.

They examined both short and long IPI, including assessments of an ordinal IPI variable that aligns with clinical guidelines and a continuous IPI variable evaluated using cubic spline analyses.

They looked at associations with non-ASD DDs in addition to ASD and also examined associations for several ASD and DD phenotypic subtypes. Finally, they assessed several factors possibly related to the underlying causal pathway.

Altogether, 3200 children enrolled in SEED and completed sufficient assessments to receive a final classification of ASD, developmental disabilities (DD), or children from the general population. Of these, 2728 children had data on maternal pregnancy history; 2725 also had data on potential confounders of interest. The sample for the current analysis was necessarily limited to second or later births – 1507.

Lead author Dr. Laura Schieve of the leading national public health institute of the United States, Centers for Disease Control and Prevention, said: ‘These findings support existing guidelines on pregnancy spacing and further highlight the association between autism and pregnancy health.’

The paper concluded that the findings suggest ASD is increased in children born in second or later births after a short or long IPI.

Access the paper Autism Spectrum Disorder and Birth Spacing: Findings from the Study to Explore Early Development (SEED) here.