Table 2.

Proportion dried blood spots (DBS) collected among subjects born in a catalogued month, by selected characteristics of subjects

	DBS Located N=199	DBS Unlocated N=13	% Collected	p-value*
Case status
Case	65	1	98
Control	134	12	92	p=0.07
Birth year
1978-1983	98	8	92
1984-1990	101	5	95	p=0.57
Born in an in-state non-federal hospital
Yes	196	6	97
No†	3	7	30	p<0.0001
Sex
Male	126	7	95
Female	73	6	92	p=0.56
Mother's race/ethnicity
Non-Hispanic white	185	13	93
Hispanic or non-white	14	0	100	p=1.0
Mother's education (college degree)
Yes	52	0	100
No	147	13	92	p=0.04
Mother smoked during pregnancy
Yes	33	6	85
No	166	7	96	p=0.02
Interview and birth residence same
Yes	76	2	98
No	123	11	92	p=0.14
Father completed interview
Yes	183	9	95
No	16	4	80	p=0.02

^*Fisher's exact, two-sided

^†Birth center, home, federal hospital or out-of-state location