Department of Economics and Business Economics

Caesarean section and risk of autism across gestational age: a multi-national cohort study of 5 million births

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  • Benjamin Hon Kei Yip, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden benyip@cuhk.edu.hk.
  • ,
  • Helen Leonard, Telethon Kids Institute.
  • ,
  • Sarah Stock, MRC Centre for Reproductive Health, University of Edinburgh Queen's Medical Research Institute, Edinburgh, UK.
  • ,
  • Camilla Stoltenberg, Norwegian Institute of Public Health, Oslo, Norway.
  • ,
  • Richard W Francis, Telethon Kids Institute.
  • ,
  • Mika Gissler, National Institute for Health and Welfare, Helsinki, Finland.
  • ,
  • Raz Gross, Department of Epidemiology and Preventive Medicine, Tel Aviv University, Tel Aviv, Israel.
  • ,
  • Diana Schendel
  • Sven Sandin, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.

BACKGROUND: The positive association between caesarean section (CS) and autism spectrum disorder (ASD) may be attributed to preterm delivery. However, due to lack of statistical power, no previous study thoroughly examined this association across gestational age. Moreover, most studies did not differentiate between emergency and planned CS.

METHODS: Using population-based registries of four Nordic countries and Western Australia, our study population included 4 987 390 singletons surviving their first year of life, which included 671 646 CS deliveries and 31 073 ASD children. We used logistic regression to estimate odds ratios (OR) and their 95% confidence intervals (CI) for CS, adjusted for gestational age, site, maternal age and birth year. Stratified analyses were conducted by both gestational age subgroups and by week of gestation. We compared emergency versus planned CS to investigate their potential difference in the risk of ASD.

RESULTS: Compared with vaginal delivery, the overall adjusted OR for ASD in CS delivery was 1.26 (95% CI 1.22-1.30). Stratified ORs were 1.25 (1.15-1.37), 1.16 (1.09-1.23), 1.34 (1.28-1.40) and 1.17 (1.04-1.30) for subgroups of gestational weeks 26-36, 37-38, 39-41 and 42-44, respectively. CS was significantly associated with risk of ASD for each week of gestation, from week 36 to 42, consistently across study sites (OR ranged 1.16-1.38). There was no statistically significant difference between emergency and planned CS in the risk of ASD.

CONCLUSION: Across the five countries, emergency or planned CS is consistently associated with a modest increased risk of ASD from gestational weeks 36 to 42 when compared with vaginal delivery.

Original languageEnglish
JournalInternational Journal of Epidemiology
Volume46
Issue2
Pages (from-to)429–439
Number of pages11
ISSN0300-5771
DOIs
Publication statusPublished - 2017

    Research areas

  • Adolescent, Adult, Autism Spectrum Disorder/epidemiology, Cesarean Section/adverse effects, Child, Cohort Studies, Emergencies, Female, Gestational Age, Humans, Infant, Newborn, International Cooperation, Logistic Models, Male, Pregnancy, Registries, Scandinavian and Nordic Countries/epidemiology, Western Australia/epidemiology, Young Adult

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