Table 1.

Selected characteristics of study subjects, mean (std) or n (percentage).

Characteristics	Cases (244)	Controls (453)	P-value*
Maternal age at sampling (years)	27.0 (4.2)	26.9 (4.1)	0.76
Gestational day	70.7 (14.5)	70.2 (14.2)	0. 64
Age at diagnosis (years)	45.6 (6.5)	-
Lag time (years)	18.6 (6.1)	-
Primi-gravida	201 (82%)	356 (77%)	0.23
Maternal weight at enrolment (kg)	61.2 (8.3)	61.6 (9.5)	0.61
Maternal height at enrolment (cm)	165.0 (5.6)	165.3 (5.7)	0.46
Mothers reporting smoking at enrolment#	75 (31%)	121 (27%)	0.26
Cotinine ≥ 25 ng/mL	89 (37%)	147 (33%)	0.28
Child sex (boy)	135 (55%)	237 (52%)	0.45
Child birth weight (g)	3,481 (443)	3,447 (460)	0.32
Child birth height (cm)	50.4 (2.2)	50.4 (2.0)	0.83
Placental weight (g)**	575 (125)	580 (121)	0.64
Parity by index date			0.10
1	59 (24%)	88 (19%)
2	129 (53%)	230 (51%)
>2	56 (23%)	135 (30%)

^*Chi-square test for categorical variables and mixed-effects regression models for continuous variables;

^#237 cases and 439 controls with data on smoking status at enrolment;

^**208 cases and 391 controls with data on placental weight.