Table 7

A comparison of the results from the present, Sweden, Norway, California, and England and Wales studies.

Birth defect
Study area
Fixed-Effects Model Summary OR (95 % CI)
Random-Effects Model Summary OR (95% CI)
Q-statistic/P-value*

Anencephalus
Norway 2002
1.13 (0.74–1.73)
1.15 (0.56–2.36)
7.55/0.056

California 2003 (1)




California 2003 (2)




Taiwan 2008




Norway 2002
0.85 (0.51–1.43)
0.91 (0.40–2.51)
4.23/0.121

California 2003 (1)




California 2003 (2)




Norway 2002
0.98 (0.61–1.59)
0.98 (0.38–2.51)
6.19/0.045

California 2003 (1)




Taiwan 2008




Norway 2002
1.73 (1.01–2.96)
1.73 (1.01–2.96)
0.96/0.619

California 2003 (2)




Taiwan 2008



Cleft palate
Norway 2002
1.00 (0.87–1.15)
1.10 (0.82–1.48)
4.50/0.212

California 2003 (2)




Taiwan 2008




England and Wales 2007




Norway 2002
1.43 (0.97–2.10)
1.43 (0.97–2.10)
0.74/0.690

California 2003 (2)




Taiwan 2008




Norway 2002
0.95 (0.83–1.10)
0.95 (0.83–1.10)
0.05/0.976

California 2003 (2)




England and Wales 2007




California 2003 (2)
1.00 (0.87–1.15)
1.13 (0.77–1.66)
4.49/0.106

Taiwan 2008




England and Wales 2007



Cleft lip with/without palate
Norway 2002
0.95 (0.85–1.06)
0.95 (0.85–1.06)
2.76/0.431

California 2003 (2)




Taiwan 2008




England and Wales 2007




Norway 2002
1.00 (0.78–1.27)
1.01 (0.75–1.37)
2.58/0.276

California 2003 (2)




Taiwan 2008




Norway 2002
0.95 (0.84–1.06)
0.97 (0.76–1.24)
2.71/0.258

California 2003 (2)




England and Wales 2007




California 2003 (2)
0.96 (0.86–1.07)
0.98 (0.82–1.15)
2.54/0.281

Taiwan 2008




England and Wales 2007



Ventricular septal defects
Norway 2002
1.59 (1.21–2.07)
1.59 (1.21–2.07)
0.74/0.692

Taiwan 2008




England and Wales 2007




Norway 2002
1.81 (1.21–2.71)
1.81 (1.21–2.71)
0.0001/0.99

Taiwan 2008



Hydrocephalus
Sweden 2000
0.95 (0.59–1.50)
1.21 (0.52–2.81)
3.76/0.152

Norway 2002




Taiwan 2008



Obstructive urinary tract defects
Norway 2002
1.61 (0.85–3.03)
1.61 (0.85–3.03)
0.22/0.638

Taiwan 2008



Atrial septal defects
Norway 2002
0.97 (0.61–1.52)
0.97 (0.61–1.52)
0.30/0.59

Taiwan 2008




*P < 0.05 indicates that a random-effects model is more appropriate.

*Sweden 2000 [14]; California 2003(1): Shaw et. al. Study 1 [11]; California 2003(1): Shaw et. al. Study 2 [11] Norway 2007 [12]; England and Wales 2007 [13]; Taiwan 2008: the present study.

Hwang et al. Environmental Health 2008 7:23   doi:10.1186/1476-069X-7-23