. 2016 Feb 22;11(2):e0149818. doi: 10.1371/journal.pone.0149818

Table 4. Adjusted odds ratio (OR) and 95% confidence interval (95%CI) of preeclampsia.

Variables	Number of participants	Preeclampsia (%)	ORs (95% CI)^*
All women
Folic acid supplementation
No	404	17 (4.21)	Reference
Yes	7265	228 (3.14)	0.58 (0.33, 1.02)
Folic acid supplementation alone
No	404	17 (4.21)	Reference
Yes	625	24 (3.84)	0.76 (0.36, 1.62)
RBC folate
>10^th percentile	766	19 (2.48)	Reference
< = 10^th percentile	92	3 (3.26)	1.99 (0.53, 7.38)
Women with high risk pregnancy^**
Folic acid supplementation
No	56	8 (14.29)	Reference
Yes	824	76 (9.22)	0.42 (0.18, 0.98)
Folic acid supplementation alone
No	56	8 (14.29)	Reference
Yes	74	6 (8.11)	0.17 (0.03, 0.95)
RBC folate
>10^th percentile	94	5 (5.32)	Reference
< = 10^th percentile	6	1 (16.67)	4.60 (0.29, 73.013)
Women with low risk pregnancy
Folic acid supplementation
No	348	9 (2.59)	Reference
Yes	6441	152 (2.36)	0.75 (0.34, 1.63)
Folic acid supplementation alone
No	348	9 (2.59)	Reference
Yes	551	18 (3.27)	1.35 (0.52, 3.51)
RBC folate
>10^th percentile	672	14 (2.08)	Reference
< = 10^th percentile	86	2 (2.33)	1.55 (0.31, 7.64)

*Adjusted for maternal age, previous health problem (chronic hypertension, history of preeclampsia, diabetes), smoking, and parity.

** High risk of pregnancy: body mass index > = 35, previous preeclampsia history, chronic hypertension, diabetes, multiple pregnancy.