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Table 1 Summary risk estimates of the overall and subgroup analyses on maternal use of folic acid supplements during pregnancy and risk of autism spectrum disorders in children

From: The association between maternal use of folic acid supplements during pregnancy and risk of autism spectrum disorders in children: a meta-analysis

Subgroups No. (cases) No. (studies) Risk estimate (95% CI) Heterogeneity test I 2 (%) P value
All studies 4514 16 0.771(0.641–0.928) 59.7 0.001
 Study design
  Prospective 2794 5 0.903(0.786–0.998) 42.6 0.138
  Case-control 1720 11 0.435(0.264–0.717) 66.0 0.001
 Ethnicity
  Asian 1581 8 0.669(0.461–0.972) 64.9 0.006
  European 2258 3 0.844(0.683–0.993) 53.5 0.116
  American 675 5 0.405(0.165–0.994) 68.0 0.014