Table 1

Relation between reported use of folic acid supplements and blood folate levels

Use of folic acid		(N)		Folate levels
Ever taken	Took before conception	(N)		Taking now	Median	IQR^1-150	Range
				Serum Folate levels (nmol/l)
No	No	No	(379)	13	9–20	2–73
Yes	No	No	(271)	18	12–27	4–126
Yes	Yes	No	(128)	24	17–34	4–72
Yes	No	Yes	(404)	31	21–47	3–344
Yes	Yes	Yes	(247)	40	29–52	10–442

				Red cell folate levels (nmol/l)
No	No	No	(370)	358	270–471	7–1206
Yes	No	No	(269)	462	367–596	0–3032
Yes	No	Yes	(393)	492	374–664	23–2411
Yes	Yes	No	(122)	658	444–816	150–1826
Yes	Yes	Yes	(241)	693	553–877	45–1876

↵1-150 IQR = interquartile range.