Table 1 Baseline characteristics of study participants by number of pregnancies
|  | Total | 0 pregnancies | 1 pregnancy | 2 pregnancies | 3 pregnancies | 4 pregnancies | ≥5 pregnancies |
|---|---|---|---|---|---|---|---|
Number of women (N) | 289,573 | 2809 (1.0) | 26,891 (9.3) | 76,137 (26.3) | 76,802 (26.5) | 50,779 (17.5) | 56,155 (19.4) |
Rural, % | 56.8 | 40.1 | 37.9 | 56.3 | 58.4 | 59.6 | 61.0 |
Age, years | 50.5 (10.3) | 49.9 (11.5) | 44.2 (7.7) | 46.1 (8.0) | 49.4 (9.0) | 53.1 (9.9) | 58.8 (10.4) |
Education level, % | |||||||
 Primary or below | 56.8 | 43.3 | 32.6 | 49.3 | 56.1 | 62.6 | 74.7 |
 Secondary or above | 43.2 | 56.7 | 67.4 | 50.7 | 43.9 | 37.4 | 25.3 |
Household income, % | |||||||
 Low | 10.2 | 12.1 | 5.3 | 6.8 | 8.4 | 11.5 | 18.4 |
 Middle | 49.1 | 52.3 | 43.7 | 46.9 | 48.9 | 50.6 | 53.5 |
 High | 40.7 | 35.6 | 51.1 | 46.4 | 42.8 | 37.9 | 28.1 |
Current smoking, % | 4.9 | 6.7 | 3.4 | 2.9 | 4.0 | 5.6 | 8.9 |
Regular alcohol use, % | 36.5 | 42.1 | 41.7 | 35.7 | 36.3 | 36.4 | 35.2 |
Physical activity (MET hours/day) | 17.2 (11.0, 28.7) | 14.8 (9.3, 24.7) | 20.3 (12.8, 31.8) | 20.4 (12.3, 32.3) | 18.3 (11.2, 30.0) | 15.7 (10.3, 26.6) | 12.9 (8.4, 21.1) |
Systolic blood pressure, mmHg | 129.4 (21.8) | 127.7 (23.0) | 123.0 (18.6) | 126.1 (19.9) | 128.7 (21.3) | 131.6 (22.3) | 136.0 (23.8) |
Body mass index, kg/m2 | 23.8 (3.4) | 23.4 (3.8) | 23.6 (3.3) | 23.7 (3.3) | 23.8 (3.4) | 23.9 (3.5) | 23.8 (3.6) |
History of hypertension, % | 10.2 | 9.0 | 5.5 | 7.2 | 9.7 | 12.4 | 15.6 |
History of diabetes, % | 2.9 | 2.7 | 1.4 | 1.8 | 2.6 | 3.3 | 4.9 |
Pregnancy loss, % | |||||||
 History of miscarriage | 9.8 | – | 0.6 | 2.3 | 7.3 | 12.2 | 21.2 |
 History of induced abortion | 52.8 | – | 1.3 | 44.4 | 60.2 | 65.1 | 65.1 |
 History of stillbirth | 6.5 | – | 0.3 | 1.2 | 4.0 | 7.2 | 14.7 |
Ever use of oral contraceptives, % | 9.8 | 2.2 | 5.6 | 8.4 | 10.9 | 11.7 | 11.0 |