Table 1.

Quality assessment of included studies (points scored, see box 2)

Included study	Selection	Comparability	Size	Outcome 1*	Outcome 2†
Prospective cohort studies
Arngrimsson 199027	1	1	1	1	2
Cincotta 199828	1	1	1	1	2
Davies 197025	1	2	2	1	2
Dukler 200123	1	2	2	1	2
Gamer 199035	1	2	2	2	2
Hartikainen 199814	1	2	2	1	2
Pattison 199338	1	1	1	1	2
Sattar 200155	1	2	2	1	2
Sibai 198621	1	2	2	1	2
Sibai 199554	1	2	2	1	2
Sibai 199749	1	2	2	1	2
Thadhani 199948	1	2	1	1	2
Yasuda 199539	1	1	1	2	2
Retrospective cohort studies
Basso 200145	1	2	2	2	1
Bianco 19968	1	1	2	1	1
Bianco 199846	1	2	2	1	1
Bowers 199950	1	2	1	1	2
Bradford 198956	1	2	1	1	2
Brown 199157	1	1	2	2	2
Campbell 198520	1	1	2	2	2
Conde-Agudelo44	1	2	2	1	1
Coonrod 199510	1	1	1	1	1
Khan 199613	1	2	2	1	2
Konje 199258	1	1	2	2	2
Lawoyin 199611	1	1	1	1	2
Lee 200012	1	2	2	2	2
Makkonen 200022	1	2	2	1	2
Martinell 199037	1	2	1	1	2
Maxwell 200132	1	2	1	2	2
McCowan 199636	1	1	1	1	2
Reiss 198753	1	2	1	1	2
Ros 199831	1	2	2	2	1
Saftlas 19909	1	2	2	2	1
Savvidou 200133	1	2	2	2	2
Sebire 200152	1	2	2	1	1
Skjaerven 200243	1	2	2	1	2
Stamilo 200019	1	2	1	2	2
Stone 199416	1	2	1	1	2
Case-control studies
Banias 199226	1	2	1	1	2
Branch 198940	1	1	1	1	2
Chen 200017	1	1	2	1	2
Dreyfus 200142	1	2	2	1	2
Eskenazi 199115	1	2	2	2	1
Fields 199647	1	1	1	1	2
Moore 198324	1	2	1	1	2
Odegard 200018	1	1	2	1	2
Reiss 198753	1	2	1	1	2
Santema 199530	1	2	2	2	2
Skupski 199634	1	2	1	2	2
Sletnes 199241	1	1	1	1	2
Sutherland 198129	1	2	2	1	2
Van Hoorn 200251	1	1	1	2	2

^*Definition of pre-eclampsia.

^†How diagnosis of pre-eclampsia is made.