Table 5.

Association between Amount of Folic Acid Supplementation One Month Before Conception and During First Trimester of Pregnancy, and Asthma in the Offspring at Six Years of Age. Results are presented as Odds Ratio (OR) with 95% Confidence Intervals (95% CI) and p for trend

		Unadjusted			Adjusteda
Folic Acid Use	n	OR	95% CI	P trend	OR	95% CI	P trend
Month before Conception
No use	731	Ref			Ref
<400 mcg	89	0.93	0.52-1.67		1.29	0.70-2.40
400-800 mcg	625	0.58	0.42-0.79		0.89	0.62-1.27
>800 mcg	54	0.68	0.30-1.54	0.001	1.02	0.44-2.40	0.70
Month 1 of pregnancy
No use	586	Ref			Ref
<400 mcg	87	0.96	0.54-1.72		1.31	0.71-2.41
400-800 mcg	746	0.56	0.41-0.76		0.82	0.58-1.17
>800 mcg	80	0.61	0.31-1.22	<0.001	0.94	0.46-1.97	0.33
Month 2 of pregnancy
No use	281	Ref			Ref
<400 mcg	92	0.64	0.32-1.30		1.03	0.49-2.14
400-800 mcg	1009	0.84	0.59-1.20		1.45	0.97-2.16
>800 mcg	117	0.49	0.25-0.98	0.13	0.88	0.42-1.82	0.30
Month 3 of pregnancy
No use	191	Ref			Ref
<400 mcg	69	0.82	0.39-1.71		0.80	0.37-1.72
400-800 mcg	1144	0.73	0.49-1.08		0.96	0.63-1.47
>800 mcg	95	0.56	0.27-1.16	0.07	0.79	0.37-1.68	0.77
First trimester overall
No use	118	Ref			Ref
<400	342	1.08	0.63-1.87		1.34	0.76-2.35
400-800	953	0.73	0.44-1.21		1.18	0.68-2.04
>800	86	0.41	0.17-1.01	0.006	0.73	0.28-1.87	0.70

^aAdjusted for household annual income (40 000 USD <vs.>=40 000 USD), maternal marital status (married vs not married) and physician diagnosed maternal asthma (yes/no).