Table 1:
Baseline and birth characteristics of hospital live births and stillbirths in Ontario between Apr. 1, 2012, and Mar. 3, 2017, before and after propensity score weighting, by tetanus–diphtheria–acellular pertussis vaccination status (cohort 1)
| Characteristic | Total population, no. (%) of mothers n = 615 213 |
Unweighted cohort, no. (%) of mothers | Standardized difference† | IPTW-weighted cohort,* % of mothers | Standardized difference† | ||
|---|---|---|---|---|---|---|---|
| Vaccinated n = 11 519 |
Unvaccinated n = 603 694 |
Vaccinated | Unvaccinated | ||||
| Maternal age, yr | |||||||
| < 20 | 14 249 (2.3) | 182 (1.6) | 14 067 (2.3) | 0.05 | 3.0 | 2.3 | 0.04 |
| 20–24 | 66 102 (10.7) | 788 (6.8) | 65 314 (10.8) | 0.14 | 10.2 | 10.9 | 0.02 |
| 25–29 | 165 891 (27.0) | 3272 (28.4) | 162 619 (26.9) | 0.03 | 28.1 | 26.9 | 0.03 |
| 30–34 | 225 692 (36.7) | 4536 (39.4) | 221 156 (36.6) | 0.06 | 35.4 | 36.6 | 0.02 |
| ≥ 35 | 143 279 (23.3) | 2741 (23.8) | 140 538 (23.3) | 0.01 | 23.3 | 23.3 | 0.00 |
| Year of conception | |||||||
| 2011/12 | 95 499 (15.5) | 385 (3.3) | 95 114 (15.8) | 0.43 | 19.0 | 16.0 | 0.08 |
| 2012/13 | 124 714 (20.3) | 1323 (11.5) | 123 391 (20.4) | 0.25 | 20.4 | 20.6 | 0.00 |
| 2013/14 | 124 990 (20.3) | 2043 (17.7) | 122 947 (20.4) | 0.07 | 19.1 | 20.4 | 0.03 |
| 2014/15 | 124 163 (20.2) | 2426 (21.1) | 121 737 (20.2) | 0.02 | 19.3 | 20.1 | 0.02 |
| 2015/16 | 124 232 (20.2) | 4478 (38.9) | 119 754 (19.8) | 0.43 | 18.8 | 19.5 | 0.02 |
| 2016/17 | 21 615 (3.5) | 864 (7.5) | 20 751 (3.4) | 0.18 | 3.4 | 3.4 | 0.00 |
| Parity | |||||||
| 0 | 272 399 (44.3) | 6027 (52.3) | 266 372 (44.1) | 0.16 | 43.0 | 44.0 | 0.02 |
| ≥ 1 | 342 814 (55.7) | 5492 (47.7) | 337 322 (55.9) | 0.16 | 57.0 | 56.0 | 0.02 |
| Multiple birth | 11 734 (1.9) | 155 (1.3) | 11 579 (1.9) | 0.05 | 2.0 | 1.9 | 0.00 |
| Baby’s sex‡ | |||||||
| Female | 298 032 (48.4) | 5579 (48.6) | 292 453 (48.7) | 0.00 | 48.6 | 48.4 | 0.00 |
| Male | 313 896 (51.0) | 5904 (51.4) | 307 992 (51.3) | 0.00 | 51.4 | 51.6 | 0.00 |
| Preexisting maternal medical condition§ | |||||||
| Asthma | 1501 (0.2) | 25 (0.2) | 1476 (0.2) | 0.01 | 0.3 | 0.3 | 0.01 |
| Chronic hypertension | 2358 (0.4) | 39 (0.3) | 2319 (0.4) | 0.01 | 0.4 | 0.4 | 0.01 |
| Diabetes | 4846 (0.8) | 55 (0.5) | 4791 (0.8) | 0.04 | 0.9 | 0.8 | 0.01 |
| Heart disease | 2971 (0.5) | 50 (0.4) | 2921 (0.5) | 0.01 | 0.5 | 0.5 | 0.01 |
| Thyroid disease | 7135 (1.2) | 199 (1.7) | 6936 (1.1) | 0.05 | 1.2 | 1.1 | 0.00 |
| Drug dependence or tobacco use | 3326 (0.5) | 37 (0.3) | 3289 (0.5) | 0.03 | 0.5 | 0.6 | 0.01 |
| Maternal obesity (body mass index > 30.0) | 3436 (0.6) | 47 (0.4) | 3389 (0.6) | 0.02 | 0.5 | 0.6 | 0.01 |
| Neighbourhood median family income quintile | |||||||
| 1 (lowest) | 131 512 (21.4) | 2240 (19.4) | 129 272 (21.4) | 0.05 | 22.7 | 21.5 | 0.03 |
| 2 | 123 738 (20.1) | 2466 (21.4) | 121 272 (20.1) | 0.03 | 18.6 | 20.1 | 0.04 |
| 3 | 127 176 (20.7) | 2215 (19.2) | 124 961 (20.7) | 0.04 | 21.2 | 20.7 | 0.01 |
| 4 | 129 987 (21.1) | 2372 (20.6) | 127 615 (21.1) | 0.01 | 21.7 | 21.1 | 0.01 |
| 5 (highest) | 102 800 (16.7) | 2226 (19.3) | 100 574 (16.7) | 0.07 | 16.0 | 16.6 | 0.02 |
| Rural residence | 57 263 (9.3) | 968 (8.4) | 56 295 (9.3) | 0.03 | 9.4 | 9.3 | 0.00 |
| LHIN group | |||||||
| Central | 204 512 (33.2) | 3730 (32.4) | 200 782 (33.3) | 0.02 | 33.2 | 33.3 | 0.00 |
| East | 148 737 (24.2) | 4410 (38.3) | 144 327 (23.9) | 0.31 | 21.1 | 23.6 | 0.06 |
| North | 32 305 (5.3) | 401 (3.5) | 31 904 (5.3) | 0.09 | 3.8 | 5.3 | 0.07 |
| Toronto | 57 397 (9.3) | 1390 (12.1) | 56 007 (9.3) | 0.09 | 9.9 | 9.2 | 0.02 |
| West | 172 262 (28.0) | 1588 (13.8) | 170 674 (28.3) | 0.36 | 32.0 | 28.5 | 0.08 |
| Maternal world region of origin | |||||||
| North America | 473 002 (76.9) | 8706 (75.6) | 464 296 (76.9) | 0.03 | 77.4 | 77.0 | 0.01 |
| Asia | 89 566 (14.6) | 2198 (19.1) | 87 368 (14.5) | 0.12 | 14.1 | 14.4 | 0.01 |
| Europe | 12 876 (2.1) | 164 (1.4) | 12 712 (2.1) | 0.05 | 2.1 | 2.1 | 0.00 |
| Africa | 12 467 (2.0) | 160 (1.4) | 12 307 (2.0) | 0.05 | 2.3 | 2.0 | 0.02 |
| Caribbean | 8689 (1.4) | 78 (0.7) | 8611 (1.4) | 0.07 | 1.3 | 1.4 | 0.01 |
| Yugoslavia/Soviet Union¶ | 8172 (1.3) | 93 (0.8) | 8079 (1.3) | 0.05 | 1.3 | 1.4 | 0.00 |
| South America | 6865 (1.1) | 80 (0.7) | 6785 (1.1) | 0.05 | 1.0 | 1.1 | 0.02 |
| Central America | 3270 (0.5) | 28 (0.2) | 3242 (0.5) | 0.05 | 0.5 | 0.5 | 0.00 |
| Oceania | 306 (0.0) | 12 (0.1) | 294 (0.0) | 0.02 | 0.0 | 0.05 | 0.01 |
| Ontario Marginalization Index dimension, quintile** | |||||||
| Residential instability | |||||||
| 1 | 137 422 (22.3) | 2351 (20.4) | 135 071 (22.4) | 0.05 | 19.5 | 22.4 | 0.07 |
| 2 | 114 789 (18.7) | 2230 (19.4) | 112 559 (18.6) | 0.02 | 18.9 | 18.6 | 0.01 |
| 3 | 110 776 (18.0) | 2070 (18.0) | 108 706 (18.0) | 0.00 | 17.5 | 18.0 | 0.01 |
| 4 | 115 280 (18.7) | 2041 (17.7) | 113 239 (18.8) | 0.03 | 19.4 | 18.8 | 0.02 |
| 5 | 136 946 (22.3) | 2827 (24.5) | 134 119 (22.2) | 0.05 | 24.7 | 22.2 | 0.06 |
| Material deprivation | |||||||
| 1 | 119 103 (19.4) | 2795 (24.3) | 116 308 (19.3) | 0.12 | 20.0 | 19.2 | 0.02 |
| 2 | 120 208 (19.5) | 2380 (20.7) | 117 828 (19.5) | 0.03 | 20.4 | 19.5 | 0.02 |
| 3 | 117 009 (19.0) | 2097 (18.2) | 114 912 (19.0) | 0.02 | 18.6 | 19.0 | 0.01 |
| 4 | 117 529 (19.1) | 2121 (18.4) | 115 408 (19.1) | 0.02 | 18.8 | 19.1 | 0.01 |
| 5 | 141 364 (23.0) | 2126 (18.5) | 139 238 (23.1) | 0.11 | 22.3 | 23.1 | 0.02 |
| Dependency | |||||||
| 1 | 209 834 (34.1) | 3519 (30.5) | 206 315 (34.2) | 0.08 | 30.4 | 34.1 | 0.08 |
| 2 | 129 753 (21.1) | 2447 (21.2) | 127 306 (21.1) | 0.00 | 21.7 | 21.1 | 0.01 |
| 3 | 104 245 (16.9) | 2045 (17.8) | 102 200 (16.9) | 0.02 | 18.3 | 16.9 | 0.03 |
| 4 | 92 197 (15.0) | 1943 (16.9) | 90 254 (15.0) | 0.05 | 16.2 | 15.0 | 0.03 |
| 5 | 79 184 (12.9) | 1565 (13.6) | 77 619 (12.9) | 0.02 | 13.4 | 12.9 | 0.02 |
| Ethnic concentration | |||||||
| 1 | 81 765 (13.3) | 1379 (12.0) | 80 386 (13.3) | 0.04 | 13.4 | 13.3 | 0.00 |
| 2 | 92 146 (15.0) | 1652 (14.3) | 90 494 (15.0) | 0.02 | 15.2 | 15.0 | 0.00 |
| 3 | 104 071 (16.9) | 1942 (16.9) | 102 129 (16.9) | 0.00 | 18.0 | 16.9 | 0.03 |
| 4 | 129 709 (21.1) | 2428 (21.1) | 127 281 (21.1) | 0.00 | 21.5 | 21.1 | 0.01 |
| 5 | 207 522 (33.7) | 4118 (35.7) | 203 404 (33.7) | 0.04 | 31.9 | 33.6 | 0.04 |
| Prenatal care index†† | |||||||
| Intensive | 12 518 (2.0) | 280 (2.4) | 12 238 (2.0) | 0.03 | 1.90 | 2.0 | 0.01 |
| Adequate | 167 489 (27.2) | 4468 (38.8) | 163 021 (27.0) | 0.25 | 25.5 | 26.8 | 0.03 |
| Intermediate | 308 121 (50.1) | 5683 (49.3) | 302 438 (50.1) | 0.02 | 47.8 | 50.1 | 0.05 |
| Inadequate | 87 112 (14.2) | 894 (7.8) | 86 218 (14.3) | 0.21 | 16.3 | 14.4 | 0.05 |
| No care/missing‡‡ | 39 973 (6.5) | 194 (1.7) | 39 779 (6.6) | 0.25 | 8.5 | 6.7 | 0.07 |
Note: IPTW = inverse probability of treatment weight, LHIN = Local Health Integration Network.
Data were weighted with the use of stabilized IPTWs calculated based on propensity scores. Variables included in the propensity score model were maternal age, parity, multiple birth, baby’s sex, preexisting maternal medical conditions (chronic hypertension, diabetes, asthma, heart disease, thyroid disease), fiscal year of conception, maternal world region of birth, Ontario Marginalization Index dimensions (residential instability, material deprivation, dependency, ethnic concentration), rural residence, neighbourhood income quintile, LHIN group and prenatal care index.
Absolute standardized difference. Shaded cells indicate an imbalance (> 0.10) between vaccinated and unvaccinated mothers.
Among live birth records only (i.e., cohort 2).
The sum of each individual condition does not equal the number of mothers with any condition, as categories were not mutually exclusive.
As categorized in the Immigration, Refugees and Citizenship Canada Permanent Resident Database.
Quintile 1 = least marginalized, quintile 5 = most marginalized.
Adequacy of prenatal care characterized with the Revised-Graduated Prenatal Care Utilization Index (R-GINDEX).44
Fewer than 6 records had missing information on the R-GINDEX.