Table 4.

Relative risk of infant mortality, preterm birth, and low birth weight for second babies in women who changed partner between births and those who had same partner, by level of maternal education, Norway, 1967-98

	Maternal level of education
	Low (≤10 years)		Medium (11-14 years)		High (≥14 years)
Pregnancy outcome	Proportion	Relative risk*(95% CI)	Proportion	Relative risk*(95% CI)	Proportion	Relative risk*(95% CI)
Infant mortality:
Same partner	0.88	1.0	0.66	1.0	0.52	1.0
Different partner	1.16	2.0 (1.5 to 2.7)	0.82	1.8 (1.5 to 2.1)	0.65	1.6 (1.0 to 2.6)
Preterm birth†:
Same partner	4.6	1.0	3.7	1.0	3.1	1.0
Different partner	7.8	1.8 (1.6 to 2.0)	7.4	2.0 (1.9 to 2.1)	7.7	2.6 (2.2 to 3.0)
Low birth weight†:
Same partner	3.7	1.0	2.7	1.0	2.1	1.0
Different partner	7.1	2.0 (1.7 to 2.3)	6.6	2.5 (2.3 to 2.6)	7.0	3.8 (3.3 to 4.5)

^*Adjusted for maternal age (<20, 20-24, 25-29, etc), interval between births (two year categories), and period of birth (1967-76, 1977-86, 1987-98).

^†For definition see footnote to table 3.