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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