TABLE 2—

Associations Between Parity and Pregnancy Outcomes: Cohort of Scottish Women, 1991–2001

Outcome	Nulliparous (n = 84 701), No. (%)	Multiparous (n = 102 589), No. (%)	Odds Ratioa (95% Confidence Interval)
Overall preterm delivery	5280 (6.2)	4912 (4.8)	1.32 (1.27, 1.38)
Spontaneous preterm delivery	3101 (3.7)	2734 (2.7)	1.39 (1.32, 1.46)
Elective preterm delivery	2179 (2.6)	2178 (2.1)	1.22 (1.15, 1.29)
Neonatal death	203 (0.24)	135 (0.13)	1.82 (1.47, 2.27)
ELBW infant	298 (0.35)	177 (0.17)	2.04 (1.69, 2.46)
ELBW infant surviving to 1 year	162 (0.19)	91 (0.09)	2.16 (1.67, 2.80)
Preeclampsia	3272 (3.9)	1645 (1.6)	2.47 (2.32, 2.62)

Note. ELBW = extremely low birthweight. All outcomes were significant at P < .001.

^aEstimated via logistic regressions clustered on maternal identifiers.