Table 2.
Percent of population with maternal characteristics*
| All women (n = 71,200) | Primigravidas (n = 24,000) | Multigravidas | |||
|---|---|---|---|---|---|
| Previous PTB (n = 4,000) | No previous PTB | ||||
| Previous early pregnancy loss a (n = 21,300) | No previous early pregnancy loss (n = 21,600) | ||||
| Percent of sample | 33.8 | 5.7 | 30.0 | 30.5 | |
| Determinants | |||||
| Prepregnancy BMI | |||||
| <18.5 | 6.0 | 7.1 | 6.2 | 5.3 | 5.4 |
| 18.5-24.9 | 59.7 | 63.3 | 51.3 | 58.1 | 58.4 |
| 25.0-29.9 | 20.9 | 17.6 | 22.9 | 23.1 | 22.3 |
| ≥30 | 13.5 | 12.0 | 19.6 | 13.5 | 13.9 |
| Gestational weight gain | |||||
| <recommended | 18.6 | 16.6 | 18.0 | 19.4 | 20.2 |
| =recommended | 23.0 | 22.1 | 23.2 | 22.3 | 24.9 |
| >recommended | 59.4 | 61.3 | 58.7 | 58.3 | 54.9 |
| Smoked 3rd trimester | 10.4 | 7.7 | 17.2 | 13.7 | 10.0 |
| Covariates | |||||
| Maternal age | |||||
| ≤24 | 15.3 | 23.6 | 11.9 | 12.4 | 9.5 |
| 25-29 | 34.1 | 40.4 | 27.7 | 29.0 | 33.5 |
| 30-34 | 33.4 | 26.1 | 37.7 | 35.4 | 37.8 |
| ≥35 | 17.5 | 9.8 | 22.7 | 23.2 | 19.3 |
| Maternal education | |||||
| Less than high school | 6.8 | 5.1 | 12.4 | 7.8 | 6.7 |
| High school graduate | 19.4 | 17.7 | 22.7 | 20.3 | 19.8 |
| Post-secondary diploma | 37.7 | 38.1 | 41.6 | 36.8 | 37.4 |
| University graduate | 36.1 | 39.2 | 23.3 | 35.2 | 36.1 |
| Low-income-cut-off (LICO) | |||||
| ≤LICO | 18.0 | 14.9 | 26.2 | 19.1 | 19.1 |
| >LICO | 74.0 | 75.3 | 69.1 | 74.1 | 74.0 |
| Missing | 8.0 | 9.8 | 4.7 | 6.9 | 6.9 |
| Short stature | 6.4 | 5.6 | 6.8 | 5.8 | 7.7 |
| World region of birth | |||||
| Canada | 76.7 | 77.8 | 82.2 | 76.4 | 74.9 |
| Europe/Western nations | 6.0 | 5.8 | 4.4 | 6.4 | 5.9 |
| Africa/Caribbean | 2.3 | 2.2 | 3.4 | 2.6 | 1.9 |
| Middle East/North Africa | 2.6 | 2.6 | 2.3 | 1.9 | 3.3 |
| Latin America | 2.3 | 1.8 | 1.3 | 2.2 | 3.2 |
| East Asia/South East Asia/Pacific Islands | 5.7 | 5.4 | 3.0 | 6.4 | 5.7 |
| South Asia | 4.5 | 4.5 | 3.5 | 4.1 | 5.1 |
| Medical conditions prior to pregnancy | 15.2 | 14.3 | 20.5 | 16.6 | 13.8 |
| Medical conditions during pregnancy | 24.4 | 24.8 | 32.2 | 25.1 | 21.8 |
| Depression prior to pregnancy | 15.5 | 13.8 | 20.2 | 17.3 | 14.6 |
| Perceived stress during pregnancy | |||||
| Not stressful | 43.1 | 46.4 | 34.2 | 41.6 | 42.6 |
| Somewhat stressful | 44.9 | 44.7 | 47.6 | 44.7 | 45.0 |
| Very stressful | 12.0 | 8.9 | 18.2 | 13.8 | 12.4 |
| No support during pregnancy | 12.8 | 10.0 | 16.8 | 14.7 | 13.3 |
*Subgroup sample sizes do not add up to the total due to rounding to the nearest 100, as explained in the methods. Abbreviations: PTB – preterm birth, BMI – body mass index.
aEarly pregnancy loss - miscarriage, abortion and/or ectopic pregnancy.