Table 2.

Temporal changes in maternal and infant characteristics, Canada (excluding Ontario) 1991–2005

	% per birth cohort
Determinant	1991–95 (n = 1 205 375)	1996–2000 (n = 1 056 0238)	2001–05 (n = 1 016 374)	P-value for linear trend
Maternal age ≥35 years	9.8	13.3	15.1	<0.001
Primiparity	42.5	43.2	44.0	<0.001
Multiple gestation	2.1	2.5	2.9	<0.001
Male sex	51.3	51.3	51.3	0.349
Preterm birth (<37 weeks)	6.7	7.3	7.8	<0.001
Small-for-gestational age	10.3	8.9	8.0	<0.001