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Table 1 Summary characteristics of included studies

From: Comparative safety of anti-epileptic drugs during pregnancy: a systematic review and network meta-analysis of congenital malformations and prenatal outcomes

Characteristic Number of studies
(n = 96)
Percentage of total
Year of publication
 1964–1980 7 7.29
 1981–1990 19 19.79
 1991–2000 22 22.92
 2001–2005 8 8.33
 2006–2010 12 12.50
 2011–2015 28 29.17
Continent
 Europe 56 58.33
 North America 18 18.75
 Asia 10 10.42
 Trans-Continental 5 5.21
 Australia 3 3.13
 South America 3 3.13
 Africa 1 1.04
Study design
 Observational cohort 92 95.83
 Case-control 3 3.13
 Randomized clinical trial 1 1.04
Registry study
 Yes 30 31.25
 No 66 68.75
Sample size
 18–50 16 16.67
 51–100 26 27.08
 101–300 32 33.33
 301–500 8 8.33
 501–1000 2 2.08
 1001–7759 12 12.50
Number of interventionsa
 2–4 41 42.71
 5–7 30 31.25
 8–10 15 15.63
 11–17 10 10.42
Funding
 Public 21 21.88
 Private 7 7.29
 Mixed public and private 16 16.67
 Not reported 52 54.17
Indication
 Epilepsy 89 92.71
 Mixed indications 1 1.04
 Mental illness 1 1.04
 Not reported 5 5.21
Epileptic control group
 Yes 47 48.96
 No/not reported/not applicable 49 51.04
Mean maternal age, years
 24–26 11 11.46
 27–29 23 23.96
 30–34 7 7.29
 Not reported 55 57.29
Anti-epileptic drug exposure timing
 At least 1st trimester 64 66.67
 No/not reported 32 33.33
Folic acid use
 Reported 13 13.54
 Not reported 83 86.46
Alcohol use
 Reported 5 5.21
 Not reported 91 94.79
Tobacco use
 Reported 10 10.42
 Not reported 86 89.58
  1. aIncluding any relevant control group