Table 1.
Characteristics of the children included in the cohort, and that of their mothers, contrasted by standardised differences
| Characteristic | Male children (n=1 609 644) |
Female children (n=1 530 054) |
Standardised difference |
| Of the mother at the birth | |||
| Mean (SD) age, years | 29.6 (5.4) | 29.6 (5.4) | 0.00 |
| Median (IQR) number of previous live births | 1.0 (0.0–1.0) | 1.0 (0.0–1.0) | 0.00 |
| No previous live birth | 790 081 (49.1) | 751 990 (49.1) | 0.00 |
| Any previous live birth | 564 351 (35.1) | 536 816 (35.1) | 0.00 |
| Missing information on previous live birth | 3782 (0.2) | 3624 (0.2) | 0.00 |
| Maternal world region of origin | |||
| Canada/long-term resident/missing* | 1 257 056 (78.1) | 1 196 246 (78.2) | 0.00 |
| Sub-Saharan Africa | 26 199 (1.7) | 27 224 (1.7) | 0.00 |
| Caribbean | 21 602 (1.4) | 22 439 (1.4) | 0.00 |
| Middle East/North Africa | 33 720 (2.1) | 32 508 (2.1) | 0.00 |
| South Asia | 98 887 (6.1) | 93 168 (6.1) | 0.00 |
| Hispanic America | 28 318 (1.8) | 27 123 (1.8) | 0.00 |
| Western Nations/Europe | 59 502 (3.7) | 56 185 (3.7) | 0.00 |
| East Asia/Pacific | 82 410 (5.1) | 76 941 (5.0) | 0.00 |
| Of the child | |||
| Mean (SD) birth weight, g | 3440 (585) | 3322 (555) | 0.21 |
| Mean (SD) gestational age at birth, weeks | 38.0 (1.8) | 38.0 (1.8) | 0.02 |
| <28 | 3734 (0.2) | 3418 (0.2) | 0.00 |
| 28–31 | 10 089 (0.6) | 8377 (0.6) | 0.01 |
| 32–36 | 109 153 (6.8) | 92 890 (6.1) | 0.03 |
| 37+ | 1 486 668 (92.4) | 1 425 369 (93.2) | 0.03 |
| Multiple birth | 46 496 (2.9) | 45 786 (3.0) | 0.01 |
| Any congenital or chromosomal anomaly diagnosed before age 1 year | 131 134 (8.2) | 96 264 (6.3) | 0.07 |
| Income quintile (Q) at age 1 year | |||
| Q1 | 350 902 (21.8) | 334 349 (21.9) | 0.00 |
| Q2 | 319 496 (19.9) | 303 669 (19.9) | 0.00 |
| Q3 | 324 957 (20.2) | 309 245 (20.2) | 0.00 |
| Q4 | 331 985 (20.6) | 314 879 (20.6) | 0.00 |
| Q5 | 273 672 (17.0) | 259 521 (17.0) | 0.00 |
| Missing | 8632 (0.54) | 8391 (0.6) | 0.00 |
| Residence at age 1 year | |||
| Urban | 1 429 301 (88.8) | 1 358 953 (88.8) | 0.00 |
| Rural | 178 576 (11.1) | 169 416 (11.1) | 0.00 |
| Missing | 1767 (0.1) | 1685 (0.1) | 0.00 |
| Median (IQR) age at end of study follow-up, year | 13.7 (7.7–20.4) | 13.7 (7.7–20.4) | 0.00 |
All data are presented as a number (%), unless otherwise indicated.
*Includes 170 women with missing information on immigrant country of origin.