The association between post-term births and autism spectrum disorders: an updated systematic review and meta-analysis

Background: This study aimed to conduct a meta-analysis to determine whether post-term birth has an increased risk of ASD.

Materials and methods: To retrieve eligible studies regarding the effect of post-term and ASD in children, major databases including PubMed, Scopus, and Web of Science were searched. A random effect model was used for meta-analysis. For assessing the quality of included studies, the GRADE checklist was used.

Results: In total, 18 records were included with 1,412,667 sample populations from 12 countries. The pooled estimates of RR and OR showed a significant association between post-term birth and ASD among children, respectively (RR = 1.34, 95% CI 1.10 to 1.58) and (OR = 1.47, 95% CI 1.03 to 1.91). There was no heterogeneity among the studies that reported the risk of ASD among children based on RR (I² = 6.6%, P = 0.301). There was high heterogeneity in the studies reported risk of ASD based on OR (I² = 94.1%, P = 0.000).

Conclusion: Post-term births still occur relatively frequently (up to 5-10%) even in developed countries. Our results showed that post-term birth is an increased risk of ASD, although high heterogeneity was found among the studies reported based on adjusted and crude forms, however, after subgroup analysis by gender, this heterogeneity disappeared among males.