TABLE 1.
Characteristics of women with 2009 H1N1 influenza during pregnancy and infants born to them and matched controls
| Any maternal flu (n = 490) | Maternal flu, not Severea (n = 408) | Controls from prior year (n = 1,446) | Controls from same year (n = 1,451) | |||||
|---|---|---|---|---|---|---|---|---|
| n | (%) | n | (%) | n | (%) | n | (%) | |
| Maternal characteristic | ||||||||
| Age in yearsb–f | ||||||||
| <=18 | 43 | (8.8) | 41 | (10.0) | 85 | (5.9) | 63 | (4.3) |
| 19–34 | 403 | (82.2) | 333 | (81.6) | 1,135 | (78.5) | 1,123 | (77.4) |
| > = 35 | 40 | (8.2) | 32 | (7.8) | 218 | (15.1) | 258 | (17.8) |
| Missing | 4 | (0.8) | 2 | (0.5) | 8 | (0.6) | 7 | (0.5) |
| Race/ethnicityb–e | ||||||||
| White non-Hispanic | 135 | (27.6) | 113 | (27.7) | 643 | (44.5) | 675 | (46.5) |
| Black non-Hispanic | 67 | (13.7) | 53 | (13.0) | 150 | (10.4) | 149 | (10.3) |
| Hispanic | 218 | (44.5) | 185 | (45.3) | 449 | (31.1) | 446 | (30.7) |
| Other | 64 | (13.1) | 54 | (13.2) | 191 | (13.2) | 169 | (11.6) |
| Missing | 6 | (1.2) | 3 | (0.7) | 13 | (0.9) | 12 | (0.8) |
| Pre-existing conditionsg | ||||||||
| Obesityb,d | 108 | (22.0) | 87 | (21.3) | 231 | (16.0) | 272 | (18.7) |
| No obesity | 295 | (60.2) | 250 | (61.3) | 993 | (68.7) | 967 | (66.6) |
| Missing | 87 | (17.8) | 71 | (17.4) | 222 | (15.4) | 212 | (14.6) |
| Diabetesb–d | 15 | (3.0) | 12 | (2.9) | 13 | (0.9) | 23 | (1.6) |
| No diabetes | 336 | (68.6) | 303 | (74.2) | 1,008 | (69.7) | 1,014 | (69.9) |
| Missing | 139 | (28.4) | 93 | (22.8) | 425 | (29.4) | 414 | (28.5) |
| Educationb–e | ||||||||
| <High school | 153 | (31.2) | 129 | (31.6) | 309 | (21.4) | 286 | (19.7) |
| High school graduate; some college | 269 | (54.9) | 230 | (56.4) | 720 | (49.8) | 714 | (49.2) |
| College graduate or more | 43 | (8.8) | 35 | (8.6) | 364 | (25.2) | 400 | (27.6) |
| Missing | 25 | (5.1) | 14 | (3.4) | 53 | (3.7) | 51 | (3.5) |
| Method of deliveryb,c | ||||||||
| C-section | 176 | (35.9) | 127 | (31.1) | 411 | (28.4) | 401 | (27.6) |
| Vaginal | 314 | (64.1) | 281 | (68.9) | 1,033 | (71.4) | 1,049 | (72.3) |
| Missing | 0 | 0 | 2 | (0.1) | 1 | (0.1) | ||
| Infant characteristic | ||||||||
| Gestational ageb,c | ||||||||
| Preterm (<37 weeks at delivery) | 75 | (15.3) | 39 | (9.6) | 146 | (10.1) | 118 | (8.1) |
| Term (> = 37 weeks at delivery) | 414 | (84.5) | 369 | (90.4) | 1,299 | (89.8) | 1,332 | (91.8) |
| Missing | 1 | (0.2) | 0 | 1 | (0.1) | 1 | (0.1) | |
| Gestational weightc,f | ||||||||
| Low birthweight (<2,500 g) | 51 | (10.4) | 22 | (5.4) | 109 | (7.5) | 75 | (5.2) |
| Normal birthweight (> = 2,500 g) | 439 | (89.6) | 386 | (94.6) | 1,336 | (92.4) | 1,376 | (94.8) |
| Missing | 0 | 0 | 1 | (0.1) | 0 | |||
| Small-for-gestational-age | ||||||||
| <10th centile | 43 | (8.8) | 33 | (8.1) | 113 | (7.8) | 119 | (8.2) |
| > = 10th centile | 445 | (90.8) | 374 | (91.7) | 1,329 | (91.9) | 1,330 | (91.7) |
| Missing | 2 | (0.4) | 1 | (0.2) | 4 | (0.3) | 2 | (0.1) |
| 5-min Apgarb,c,f | ||||||||
| Low (<=6) | 24 | (4.9) | 9 | (2.2) | 32 | (2.2) | 18 | (1.2) |
| Normal (>6) | 463 | (94.5) | 397 | (97.3) | 1,405 | (97.2) | 1,424 | (98.1) |
| Missing | 3 | (0.6) | 2 | (0.5) | 9 | (0.6) | 9 | (0.6) |
Maternal Flu (not severe) = Not hospitalized for influenza treatment or admitted to hospital but not to the intensive care unit (ICU) for influenza treatment.
Prior-year controls compared to any maternal flu p < .01; X2 test for Heterogeneity (excluding missing).
Same-year controls compared to any maternal flu p < .05; X2 test for Heterogeneity (excluding missing).
Prior-year controls compared to nonsevere maternal flu p < .01; X2 test for Heterogeneity (excluding missing).
Same-year controls compared to nonsevere maternal flu p < .01; X2 test for Heterogeneity (excluding missing).
Prior-year controls compared to same-year controls p < .05; X2 test for Heterogeneity (excluding missing).
One state did not collect information on maternal obesity, and another state did not collect information on maternal diabetes; these states were excluded from the respective analyses.