Table 1 Risk factors for adverse perinatal outcomes in the “control” and “late motherhood” groups. The groups were defined as in Fig. 1 with the “late motherhood” groups of older women subdivided further according to age. Data are presented separately for women with zero, one, or two previous live births.
| Previous live births | Characteristic | “Control” groups (younger women) | “Late motherhood” groups (older women) | |
|---|---|---|---|---|
| Zero | Age | 22–26 years (n = 73 812) | 34–40 years (n = 21 020) | 41–46 years (n = 959) |
| Preterm birth rate | 6.5 % | 9.0 % | 13.0 % | |
| Previous stillbirths | 0.3 % | 0.8 % | 1.4 % | |
| Previous miscarriages | 9.1 % | 19.9 % | 33.6 % | |
| Previous terminations of pregnancy | 5.4 % | 10.1 % | 12.6 % | |
| Previous extrauterine pregnancies | 0.6 % | 1.9 % | 3.1 % | |
| Previous infertility treatment | 1.4 % | 9.5 % | 12.9 % | |
| One | Age | 27–31 years (n = 70 037) | 36–41 years (n = 15 564) | 42–47 years (n = 704) |
| Preterm birth rate | 4.2 % | 7.0 % | 10.7 % | |
| Previous stillbirths | 0.6 % | 1.2 % | 1.3 % | |
| Previous miscarriages | 17.3 % | 29.1 % | 40.8 % | |
| Previous terminations of pregnancy | 8.4 % | 12.4 % | 16.1 % | |
| Previous extrauterine pregnancies | 1.3 % | 2.3 % | 3.3 % | |
| Previous infertility treatment | 1.1 % | 2.8 % | 4.1 % | |
| Two | Age | 29–33 years (n = 22 347) | 39–43 years (n = 3 720) | 44–47 years (n = 179) |
| Preterm birth rate | 5.3 % | 9.5 % | 12.3 % | |
| Previous stillbirths | 0.9 % | 1.5 % | 1.7 % | |
| Previous miscarriages | 23.5 % | 33.4 % | 36.9 % | |
| Previous terminations of pregnancy | 12.9 % | 18.9 % | 22.3 % | |
| Previous extrauterine pregnancies | 1.7 % | 2.4 % | 1.1 % | |
| Previous infertility treatment | 0.5 % | 1.3 % | 2.2 % | |