Table 1 Maternal and infant characteristics among 4,409,716 Births in Canada, 2004–2020 in Canada, by conception season as specified.
Characteristic | Conception in Winter (Exposed) (n = 3689 855, 83.7%) | Conception in Summer (Un-exposed) (n = 719 861, 16.3%) | p value for difference b |
|---|---|---|---|
Period of birth | < 0.001 | ||
2004–2007 | 866,540 (23.5) | 170,620 (23.7) | |
2008–2011 | 941,343 (25.5) | 184,735 (25.6) | |
2012–2015 | 946,557 (25.7) | 183,288 (25.5) | |
2016–2019 | 935,415 (25.3) | 181,218 (25.2) | |
Geographic region | < 0.001 | ||
Far North | 43,630 (1.2) | 8537 (1.2) | |
North | 209,264 (5.7) | 41,134 (5.7) | |
North-to-South | 1,503,553 (40.7) | 296,323 (41.2) | |
South | 1,933,408 (52.4) | 373,867 (51.9) | |
Maternal age at conception (year) | < 0.01 | ||
13–18 | 134,246 (3.6) | 26,690 (3.7) | |
19–23 | 5,16,704 (14.0) | 100,343 (13.9) | |
24–28 | 1,056,251 (28.6) | 207,029 (28.8) | |
29–33 | 1,235,325 (33.5) | 240,633 (33.4) | |
34–44 | 747,329 (20.3) | 145,166 (20.2) | |
Residence | |||
Rural | 619,244 (16.8) | 122,112 (17.0) | < 0.001 |
Urban | 3,070,611 (83.2) | 597,749 (81.7) | |
Parity | < 0.0001 | ||
1st child | 1,280,636 (34.7) | 248,368 (34.5) | |
2nd child | 1,008,019 (27.3) | 198,754 (27.6) | |
≥ 3rd child | 638 675 (17.3) | 123,629 (17.2) | |
Missing | 762,525 (20.7) | 149,110 (20.7) | |
Multifetal pregnancy | |||
Yes | 52,985 (1.4) | 9908 (1.4) | < 0.001 |
No | 3,636,870 (98.6) | 709, 953 (98.6) | |
Substance use | |||
Yes | 37,669 (1.0) | 6758 (0.9) | < 0.001 |
No | 365,186 (99.0) | 713,103 (99.1) | |
Depressive disorder | |||
Yes | 11,833 (0.3) | 2402 (0.3) | 0.08 |
No | 3,678,022 (99.7) | 717,459 (99.7) | |
Hypothyroidism | |||
Yes | 26,719 (0.7) | 5188 (0.7) | 0.75 |
No | 3,663,136 (99.3) | 566,953 (99.4) | |
Gestational diabetes | |||
Yes | 240,089 (6.5) | 45,886 (6.4) | < 0.001 |
No | 3,449,766 (93.5) | 6,73,975 (93.6) | |
Tobacco smoking | |||
Yes | 19,092 (0.5) | 3742 (0.5) | 0.80 |
No | 3,170,763 (99.5) | 716,119 (99.5) | |
Obesity | |||
Yes | 59,552 (1.6) | 11,790 (1.6) | 0.14 |
No | 3,630,303 (98.4) | 70,807 (98.4) | |
Chronic illnessa | |||
Yes | 10,750 (1.5) | 55,637 (1.5) | 0.36 |
No | 3,634,211 (98.5) | 368,868 (98.5) | |
Infant sex | |||
Male | 1,892,351 (51.3) | 368,869 (51.2) | 0.50 |
Female | 1,797,504 (48.7) | 350,993 (48.8) | |
