TABLE 3.

Associations of Trimester-Specific Prenatal Active and Passive Smoking with Preeclampsia and with Gestational Hypertension in the Norwegian Mother and Child Birth Cohort

Smoking Classifications	Preeclampsia					Gestational Hypertension
	Total No.	Model 1a		Model 2b		Total No.	Model 3d		Model 4e
		OR	(95% CI)	OR	(95% CI)		OR	(95% CI)	OR	(95% CI)
First trimester
No smoke exposurec	44,482	1.00				43,846	1.00
Active smoking only	10,545	0.88	(0.78–0.98)			10,367	0.88	(0.76–1.03)
Passive smoking only	3,596	0.90	(0.76–1.07)			3,521	0.92	(0.73–1.17)
Active and passive smoking	3,306	0.82	(0.78–0.98)			3,237	0.86	(0.67–1.12)
Second trimester
No smoke exposurec	52,081	1.00				51,305	1.00
Active smoking only	3,034	0.60	(0.48–0.75)			2,998	0.64	(0.47–0.88)
Passive smoking only	4,919	0.94	(0.81–1.09)			4,806	0.94	(0.76–1.15)
Active and passive smoking	1,895	0.69	(0.54–0.88)			1,862	0.75	(0.52–1.08)
Third trimester
No smoke exposurec	53,381	1.00		1.00		52,566	1.00		1.00
Active smoking only	2,541	0.56	(0.43–0.72)	0.62	(0.44–0.89)	2,516	0.64	(0.46–0.90)	0.69	(0.42–1.13)
Passive smoking only	4,249	0.90	(0.78–1.05)	0.91	(0.76–1.10)	4,160	0.86	(0.69–1.07)	0.84	(0.64–1.09)
Active and passive smoking	1,758	0.59	(0.44–0.78)	0.60	(0.40–0.90)	1,729	0.57	(0.38–0.87)	0.51	(0.28–0.90)

CI indicates confidence interval.

^aModel 1: Adjusted for parity, maternal education, educational disparity, prepregnancy body mass index, maternal age (linear and quadratic terms), any diabetes, and excluding gestational hypertension.

^bModel 2: As above, but adjusting for smoke exposure in the previous trimester.

^cReference category.

^dModel 3: Adjusted for parity, maternal education, native language of grandparents, prepregnancy body mass index, maternal age (linear and quadratic terms), any diabetes, and excluding preeclampsia.

^eModel 4: As above, but adjusting for smoke exposure in the previous trimester.