Table IV.

Quality assessment of included studies using the NOS^*

Study nos.	Publication	Year	Selection (4 items)	Comparability† (2 items)	Exposure/outcome assessment (3 items)	Total score
#1	Francis et al15	2017	★★★★	★	★★★	8
#2	Bogdanovic et al17	2016	★★★★		★★★	7
	Gustafsson et al31	2012	★★★	★	★★★	7
	Honkaniemi et al30	2010	★★★★	★	★★★	8
#3	Bzhalava et al16	2016	★★★★		★★★	7
#4	Kumar et al37	2014	★		★★	3
#5	Tedeschi et al21	2009	★★★★	★	★★★	8
#6	Vasconcelos et al39	2008	★★★	★	★★★	7
	Kwan et al32	2007	★★★★	★★	★★	8
#7	Gustafsson et al29	2007	★★★	★	★★★	7
	Gustafsson et al28	2006	★★★		★★★	6
	Bogdanovic et al27	2004	★★★		★★★	6
	Isa et al26	2004	★★★		★★★	6
	Priftakis et al25	2003	★★★	★	★★★	7
#8	Leppik et al33	2007	★★★	★	★★★	7
	Tedeschi et al20	2007	★★★★	★	★★★	8
	Lehtinen et al40	2005	★★★★	★	★★★	8
	Lehtinen et al41	2003	★★★★	★	★★★	8
#9	Naumburg et al42	2002	★★★★	★	★★	7
#10	Dockerty et al44	1999	★★★	★	★★	6
#11	McKinney et al43	1999	★★★		★★	5
#12	Roman et al45	1997	★★	★	★★	5
#13	Buckley et al24	1994	★★★	★	★	5
#14	Gardner et al46	1990	★★★★	★	★	6
#15	McKinney et al23	1987	★★★		★★	5
#16	Fine et al48	1985	★★★	★	★★	6
#17	Van Steensel-Moll et al47	1985	★★★	★	★★	6
#18	Madden et al49	1983	★★★	★★	★★★	8
	Heinonen et al50	1973	★★★★		★★	6
#19	Bithell et al22	1973	★★★★		★★	6
	Stewart et al3	1958	★★★★		★	5
#20	Fedrick and Alberman4	1972	★★★★	★	★★★	8

^*One star is awarded if the study meets 1 assessment item.

^†The 2 items used for comparability assessment were birth date and maternal socioeconomic status (eg, educational level, income).