Preterm birth and reduced birthweight in first and second teenage pregnancies: a register-based cohort study

Table 4 Smoking confounding effect on the estimates of birthweight and preterm birth in the 2007 dataset

	Primiparous				Multiparous
	14-17 years		18-19 years		14-17 years		18-19 years
Outcomes	Not adjusted for smoking^a	Adjusted for smoking^b	Not adjusted for smoking^a	Adjusted for smoking^b	Not adjusted for smoking^a	Adjusted for smoking^b	Not adjusted for smoking^a	Adjusted for smoking^b
Birthweight estimates in grams	-28(-59, 3)	4(-27, 35)	-37(-58, -15)	-11(-32, 11)	-77(-137, -16)	-72(-132, -13)	-56(-83, -29)	-34(-61, -6)
Preterm birth OR	1.09(0.59, 2.02)	1.08(0.58, 2.00)	1.08(0.79, 1.47)	1.03(0.76, 1.41)	1.85(1.34, 2.56)	1.76(1.27, 2.44)	1.36(1.07, 1.73)	1.29(1.01, 1.65)