Table I.

Validity of retrospectively reported behaviors in the periconception window – comparison of prospective^* and retrospective data.

	Retrospectively Reported Behaviors		Based on Strict Definition of Nonuse
Prospectively Measured Behaviors*	No n (%)	Yes n (%)	Kappa	Kappa [95% CI]	% Agreement
Cigarette smoking
No	59 (72.0)	0 (0)	0.43	[0.22, 0.65]	81.8
Yes	15 (18.3)	8 (9.8)
Fish consumption
No	50 (63.3)	14 (17.7)	0.32	[0.09, 0.55]	74.7
Yes	6 (7.6)	9 (11.4)
Caffeine consumption
No	2 (2.4)	3 (3.7)	0.21	[−0.09, 0.51]	85.4
Yes	9 (11.0)	68 (82.9)
Vitamin usage
No	0 (0)	0 (0)	--	--	74.2
Yes	17 (25.8)	49 (74.2)
Alcohol consumption
No	15 (18.3)	1 (1.2)	0.20	[0.08, 0.33]	53.7
Yes	37 (45.1)	29 (35.4)

^*Prospectively measured behaviors are considered the gold standard.