Table 1. Participant and sampling characteristics.

Characteristic Median (IQR), N	US Cases (N = 89^)	US Controls (N = 69)	P-value (cases vs controls)	Chilean Cases (N = 108)	Chilean Controls (N = 105)	P-value (cases vs controls)
Age* (years)	28 (25–33) N = 89	28 (25–31) N = 69	0.2154	23 (20–30) N = 108	22 (20–27) N = 105	0.2731
Gestational age (weeks) at reported onset of symptoms	31 (28–34) N = 75	Not applicable		33 (30–35) N = 104	Not applicable
# previous births	1 (0–2) N = 86	1 (0–2) N = 69	0.5746	1 (0–2) N = 107	0(0–1) N = 105	0.0187
Gestational age at study blood draw	36 (34–37) N = 69	36 (33–38) N = 69	0.6619	38 (37–39) N = 105	39 (39–40) N = 105	<0.0001

*Age at blood draw, or for retrospectively enrolled women, reported age during the ICP-affected study pregnancy. ^Data for 89 of 90 US cases is included, as due to sample labelling uncertainty, one sample could have come from either of 2 enrolled affected women, so data from that sample is excluded here. Maternal age was analyzed using the t-test, and other variables, using the Mann-Whitney test.