Table 4.

Associations of folate acid supplementation and dietary folate intake with the risk of term-LBW and preterm-LBW.

Folic acid/folate intake duration	NBW (n= 8581)	Term-LBW (37≥weeks)		Preterm-LBW (<37 weeks)
		Cases (n= 153)	ORb (95% CI)	Cases (n= 497)	ORb (95% CI)
Folic acid supplement
Nonusers	1859	60	1.00	179	1.00
Users	6722	93	0.59 (0.41~0.85)	318	0.90 (0.72~1.12)
≤ 12 weeks	3500	60	0.65 (0.44~0.96)	202	0.92 (0.73~1.16)
>12 weeks	3222	33	0.71 (0.55~0.90)	116	0.90 (0.78~1.04)
P for trend			<0.001		<0.001
Before conception and during pregnancy	2542	23	0.40 (0.23~0.70)	106	0.96 (0.71~1.30)
<24 weeks	1179	15	0.54 (0.29~1.01)	60	0.99 (0.69~1.41)
≥24 weeks	1363	8	0.26 (0.11~0.59)	46	0.92 (0.75~1.13)
P for trend			<0.001		0.002
Before conception only	326	6	0.71 (0.29~1.70)	13	0.70 (0.38~1.30)
During pregnancy only	3854	64	0.67 (0.45~0.98)	199	0.87 (0.69~1.11)
<12 weeks	1656	29	0.65 (0.41~1.03)	109	0.91 (0.69~1.20)
≥12 weeks	2198	35	0.81 (0.64~1.02)	90	0.88 (0.76~1.02)
P for trend			0.013		0.001
Dietary folate intake (μg/day)
Before pregnancy
Q1 <116.01	2090	48	1.00	170	1.00
Q2 116.01–158.54	2186	23	0.61 (0.36~1.03)	103	0.72 (0.54~0.99)
Q3 158.54–220.88	2134	41	1.08 (0.86~1.36)	127	1.00 (0.87~1.15)
Q4 ≥220.88	2171	41	1.07 (0.89~1.29)	97	0.91 (0.81~1.03)
P for trend			0.352		0.049
During pregnancy
Q1 <149.81	2086	46	1.00	178	1.00
Q2 149.81–197.59	2125	29	0.88 (0.53~1.47)	122	1.03 (0.78~1.36)
Q3 197.59–263.67	2144	37	1.18 (0.92~1.51)	101	0.88 (0.75~1.04)
Q4 ≥263.67	2226	41	1.14 (0.92~1.42)	96	0.97 (0.84~1.12)
P for trend			0.170		0.009

^ORbadjusted for maternal age, monthly income per capita, maternal education level, smoking, maternal employ, weight gain during pregnancy, preeclampsia, cesarean section, total energy intake, dietary folate intake, or folic acid supplement.