Table 1.
Maternal influenza status and characteristics of children born 2009 – 2013 in Norway, New South Wales (Australia), and Ontario (Canada) (pooled data)
| All countries |
||||
|---|---|---|---|---|
| No. of children | Maternal influenza in pregnancy† | |||
| Characteristic | N | (%)* | n | (%)‡ |
| All children § | 1 360 629 | 14 280 | (1.0) | |
| Maternal age at delivery | ||||
| <20 | 39 388 | (2.9) | 443 | (1.1) |
| 20–24 | 175 085 | (12.9) | 2033 | (1.2) |
| 25–29 | 384 788 | (28.3) | 4384 | (1.1) |
| 30–34 | 458 829 | (33.7) | 4707 | (1.0) |
| 35–39 | 247 825 | (18.2) | 2254 | (0.9) |
| ≥40 | 54 714 | (4.0) | 459 | (0.8) |
| Maternal smoking in pregnancy | ||||
| No | 1 174 081 | (86.3) | 11 565 | (1.0) |
| Yes | 145 023 | (10.7) | 1558 | (1.1) |
| Information declined¶ | 41 525 | (3.1) | 1157 | (2.8) |
| Maternal history of epilepsy | ||||
| Yes | 5296 | (0.4) | 101 | (1.9) |
| No | 1 355 333 | (99.6) | 14 179 | (1.0) |
| Parity | ||||
| 0 | 586 634 | (43.1) | 5169 | (0.9) |
| 1 | 477 322 | (35.1) | 5760 | (1.2) |
| ≥2 | 296 673 | (21.8) | 3351 | (1.1) |
| Gestational age at birth | ||||
| Preterm (<37 weeks) | 95 994 | (7.1) | 961 | (1.0) |
| Term (≥37 weeks) | 1 264 635 | (92.9) | 13 319 | (1.1) |
| Multiple birth | ||||
| Yes | 43 765 | (3.2) | 429 | (1.0) |
| No | 1 316 864 | (96.8) | 13 851 | (1.1) |
| Season of conception ǁ | ||||
| Winter | 339 763 | (25.0) | 2589 | (0.8) |
| Spring | 324 349 | (23.8) | 2785 | (0.9) |
| Summer | 340 333 | (25.0) | 4433 | (1.3) |
| Autumn | 356 184 | (26.2) | 4473 | (1.3) |
Column percentages
Maternal influenza diagnosis during pregnancy. Norway: any diagnosis in primary care using International Classification of Primary Care code R80, or in secondary or specialist health care using International Statistical Classification of Diseases revision 10 codes J09, J10 or J11, or laboratory-confirmed pandemic influenza. NSW: any laboratory-confirmed or hospital diagnosed influenza infection during pregnancy. Ontario: any diagnosis in primary care using modified ICD-9 code 487, or in urgent or in-patient health care using International Statistical Classification of Diseases revision 10 codes J09, J10 or J11. N.b. Influenza diagnoses only valid during country-specific yearly influenza seasons
Row percentages
Children born between January 1, 2009 and December 31, 2013
Category in use for Norway data only
Northern Hemisphere : Winter (Dec-Feb), Spring (Mar-May), Summer (Jun-Aug), Autumn (Sep-Nov); Southern Hemisphere: Winter (Jun-Aug), spring (Sep-Nov), Summer (Dec-Feb), Autumn (Mar-May).