Table 3.
Relative risk of infant mortality, preterm birth, and low birthweight babies in women who changed partner between births and those who had same partner, Norway, 1967-98
|
First birth
|
Relative risk*(95% CI)
|
Second birth
|
Relative risk†(95% CI)
|
|||
|---|---|---|---|---|---|---|
| Pregnancy outcome | No of women | No (%) of events | No of women | No (%) of events | ||
| Infant mortality: | ||||||
| Same partner | 452 250 | 3 790 (0.83) | 1.0 | 453 747 | 3 051 (0.67) | 1.0 |
| Different partner | 31 386 | 260 (0.83) | 1.0 (0.9 to 1.1) | 30 521 | 267 (0.87) | 1.8 (1.6 to 2.1) |
| Preterm birth‡: | ||||||
| Same partner | 433 314 | 22 019 (5.1) | 1.0 | 409 916 | 15 922 (3.7) | 1.0 |
| Different partner | 29 028 | 1 761 (6.1) | 1.18 (1.1 to 1.2) | 28 634 | 2 183 (7.6) | 2.0 (1.9 to 2.1) |
| Low birth weight§: | ||||||
| Same partner | 455 647 | 20 237 (4.4) | 1.0 | 455 706 | 12 588 (2.8) | 1.0 |
| Different partner | 31 616 | 1 751 (5.5) | 1.27 (1.2 to 1.3) | 31 589 | 2 155 (6.8) | 2.5 (2.3 to 2.6) |
*
Adjusted for maternal age (<20, 20-24, 25-29, etc), period of birth (1967-76, 1977-86, 1987-98), and maternal level of education (≤10 years, 11-14 years, ≥14 years).
†
Adjusted for maternal age, maternal level of education, interval between births (two year categories), and period of birth.
‡
Delivery before 37 weeks of gestation, estimated from last menstrual period.
§
Birth weight less than 2500 g, regardless of length of gestation.