Table 1.

Dose-response relationship between folic acid supplementation and PE in high risk* women, OaK birth cohort study, October 2002 to December 2005.

Dose of folic acid (mg)	No. of subjects	No. (%) PE	ORs and 95% CIs**
0	33	9 (27.27)	Reference
0.1–0.9	11	1 (9.09)	0.74 (0.06, 8.88)
1.0	186	17 (9.14)	0.32 (0.10, 1.02)
1.1–1.9	18	2 (11.11)	0.24 (0.03, 1.90)
≥2.0	34	1 (2.94)	0.08 (0.01, 0.80)

*High risk in this analysis included chronic hypertension, type 1 and type 2 diabetes, history of PE, and multiple gestation; **P < 0.05 for trend test.