Table 2

Study	Study design	Study size	Methods of measuring exposure	Method of measuring outcome	Analysis with adjustment	Total
Table 2. Assessment of the quality of evidence.
Alexander et al., 1996	0	2	2	2	1	7/10
Alexander et al., 1998	0	2	2	2	2	8/10
Bonde et al., 2014	0	2	2	2	2	8/10
Eibensteiner et al., 2005	0	0	2	2	1	5/10
Farag et al., 2024	0	1	2	2	0	5/10
Hovatta et al., 1998	0	2	2	2	2	8/10
Hsu et al., 2009	0	1	2	2	2	7/10
Kasperczyk et al., 2008	0	1	2	2	1	6/10
Kuo et al., 1997	0	0	2	2	2	6/10
Mahmoud et al., 2005	0	2	2	2	2	8/10
Moran-Martinez et al., 2013	0	0	2	2	0	4/10
Naha and Chowdhury, 2006	0	1	2	2	2	7/10
Naha and Manna, 2007	0	1	2	2	2	7/10
Naha et al., 2005	0	1	2	2	2	7/10
Saaramen et al., 1987	0	2	2	2	0	6/10
Telisman et al .,2000	0	1	2	2	2	7/10
Wijesekara et al., 2020.	0	2	2	2	0	6/10

Studies with values of at least 5 are of good quality of evidence.