Table 1.

Selected sample characteristics of the study population.

	Discovery set (N = 44)		Validation set (n = 569)
Sample characteristics	Mean ± SD	Range	Mean ± SD	Range	P a
Drinking water As at recruitment (µg/L)	63.7 ± 116.5	< 1 – 510	56.0 ± 99.8b	< 1 – 629	0.898
Maternal toenail As at delivery (ng/µg)	7.0 ± 10.2	0.3 – 46.6	2.9 ± 3.8c	0.04 – 34.8	0.008
Gestational age at recruitment (weeks)	12.2 ± 2.5	6 – 16	11.4 ± 2.5	4 – 16
Gestational age at delivery (weeks)	37.6 ± 2.1	33 – 41	37.7 ± 2.2d	22 – 42	0.753
Birth weight (grams)	2923 ± 372	2080 – 4050	2824 ± 444b	1400 – 4600	0.141
Gender	n (%)		n (%)b
Male	29 (65.9%)		291 (51.2)		0.060
Female	15 (34.1%)		277 (48.8)
a. Wilcoxon rank sum test for continuous variables and chi-squared test for categorical variables.
b. n = 568
c. n = 533
c. n = 566