Demographic characteristics by body mass index (BMI) category among singleton hospital births in Ontario, Canada, Apr. 1, 2012, to Dec. 31, 2018
| Characteristic | No. (%) of pregnant people* | |||||
|---|---|---|---|---|---|---|
| Underweight n = 39 782 | Normal weight n = 347 192 | Overweight n = 165 879 | Class I obesity n = 74 951 | Class II obesity n = 32 375 | Class III obesity n = 20 999 | |
| Maternal age, yr, mean ± SD | 28.7 ± 5.5 | 30.4 ± 5.2 | 30.8 ± 5.2 | 30.7 ± 5.3 | 30.7 ± 5.2 | 30.6 ± 5.2 |
| Nulliparity | 20 578 (51.7) | 160 880 (46.3) | 65 501 (39.5) | 27 661 (36.9) | 12 006 (37.1) | 7803 (37.2) |
| Smoker | 5811 (14.6) | 31 505 (9.1) | 16 447 (9.9) | 8895 (11.9) | 4338 (13.4) | 2987 (14.2) |
| Income quintile | ||||||
| 1 (lowest) | 6454 (16.2) | 53 398 (15.4) | 30 839 (18.6) | 17 073 (22.8) | 8374 (25.9) | 5866 (27.9) |
| 2 | 6971 (17.5) | 64 888 (18.7) | 35 429 (21.4) | 17 509 (23.4) | 8059 (24.9) | 5328 (25.4) |
| 3 | 8427 (21.2) | 76 564 (22.1) | 38 432 (23.2) | 17 144 (22.9) | 7091 (21.9) | 4572 (21.8) |
| 4 | 9985 (25.1) | 86 524 (24.9) | 38 507 (23.2) | 15 258 (20.4) | 5998 (18.5) | 3490 (16.6) |
| 5 (highest) | 7945 (20.0) | 65 818 (19.0) | 22 672 (13.7) | 7967 (10.6) | 2853 (8.8) | 1743 (8.3) |
| Substance exposure | 1718 (4.3) | 7665 (2.2) | 3103 (1.9) | 1517 (2.0) | 675 (2.1) | 463 (2.2) |
| Assisted reproductive technology | 808 (2.0) | 10 863 (3.1) | 5769 (3.5) | 2988 (4.0) | 1420 (4.4) | 953 (4.5) |
| Pre-existing conditions | ||||||
| Chronic hypertension | 72 (0.2) | 1222 (0.4) | 1389 (0.8) | 1240 (1.7) | 782 (2.4) | 817 (3.9) |
| Pre-gestational diabetes | 109 (0.3) | 1743 (0.5) | 1718 (1.0) | 1360 (1.8) | 871 (2.7) | 762 (3.6) |
| Other | 6451 (16.2) | 51 350 (14.8) | 27 892 (16.8) | 15 102 (20.2) | 7557 (23.3) | 5511 (26.2) |
| Obstetrical history | ||||||
| Stillbirth | 324 (0.8) | 3390 (1.0) | 2250 (1.4) | 1169 (1.6) | 534 (1.7) | 365 (1.7) |
| Cesarean delivery | 3553 (8.9) | 42 239 (12.2) | 28 095 (16.9) | 14 827 (19.8) | 7078 (21.9) | 5044 (24.0) |
| Antenatal care | ||||||
| Family physician | 3741 (9.4) | 34 859 (10.0) | 17 422 (10.5) | 7875 (10.5) | 3224 (10.0) | 1949 (9.3) |
| Obstetrician | 24 152 (60.7) | 193 014 (55.6) | 92 843 (56.0) | 41 526 (55.4) | 17 652 (54.5) | 11 879 (56.6) |
| Family physician and obstetrician | 5585 (14.0) | 51 443 (14.8) | 26 262 (15.8) | 13 091 (17.5) | 6318 (19.5) | 4327 (20.6) |
| Midwife | 5457 (13.7) | 61 080 (17.6) | 26 031 (15.7) | 10 800 (14.4) | 4415 (13.6) | 2330 (11.1) |
| None | 145 (0.4) | 1046 (0.3) | 433 (0.3) | 203 (0.3) | 85 (0.3) | 69 (0.3) |
| Other | 702 (1.8) | 5750 (1.7) | 2888 (1.7) | 1456 (1.9) | 681 (2.1) | 445 (2.1) |
Note: SD = standard deviation.
↵* Unless indicated otherwise.