Table 3. Neonatal outcomes associated with pandemic influenza illness during pregnancy.
| Neonatal outcome | pH1N1 during pregnancy,No. (%) | No pH1N1 during pregnancy, No. (%) | Unadjusted OR (95% CI) | Adjusted OR (95% CI)1 | Adjusted OR (95% CI)2 |
|---|---|---|---|---|---|
| Low birth weight | |||||
| <2500g | 30 (16) | 25,998 (9) | 1.97 (1.33-2.91) | 1.67 (1.06-2.62) | 1.78 (1.11-2.86) |
| 2500g or more | 161 (84) | 274,400 (91) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| <1500g | 15 (8) | 4893 (2) | 5.16 (3.05-8.74) | 3.66 (1.94-6.91) | 3.93 (2.00-7.69) |
| 1500g or more | 176 (92) | 295,505 (98) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| <1000g | 6 (3) | 2518 (1) | 3.84 (1.70-8.66) | 2.47 (0.90-6.77) | 2.85 (1.03-7.90) |
| 1000g or more | 185 (97) | 297,880 (99) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Premature birth | |||||
| <37 weeks gestation | 45 (24) | 31,259 (10) | 2.65 (1.90-3.70) | 2.39 (1.64-3.49) | 2.21 (1.47-3.33) |
| 37 weeks or more | 146 (76) | 268,626 (90) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| <32 weeks gestation | 13 (7) | 5152 (2) | 4.18 (2.38-7.34) | 3.04 (1.57-5.90) | 3.21 (1.59-6.48) |
| 32 weeks or more | 178 (93) | 294,733 (98) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| <28 weeks gestation | 8 (4) | 2258 (1) | 5.77 (2.84-11.71) | 4.19 (1.82-9.63) | 3.95 (1.58-9.90) |
| 28 weeks or more | 183 (96) | 297,627 (99) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| 5-minute APGAR score | |||||
| <9 | 34 (18) | 31,848 (11) | 1.82 (1.26-2.64) | 1.56 (1.04-2.35) | 1.65 (1.08-2.52) |
| 9 or greater | 157 (82) | 267,851 (89) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Abnormal condition of newborn | |||||
| yes | 36 (19) | 37,480 (12) | 1.63 (1.14-2.35) | 1.34 (0.90-2.00) | 1.43 (0.94-2.17) |
| no | 155 (81) | 262,918 (88) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Birth Anomaly | |||||
| yes | 2 (1) | 3000 (1) | 1.05 (0.26-4.23) | 1.13 (0.28-4.55) | 1.25 (0.31-5.03) |
| no | 189 (99) | 297,398 (99) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Admitted to Neonatal ICU | |||||
| yes | 32 (17) | 22,975 (8) | 2.43 (1.66-3.55) | 1.96 (1.27-3.02) | 2.14 (1.36-3.36) |
| no | 159 (83) | 277,129 (92) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Mechanical ventilation needed >6 hours | |||||
| yes | 3 (2) | 1347 (1) | 3.54 (1.13-11.09) | 1.28 (0.18-9.16) | 1.45 (0.20-10.39) |
| no | 188 (98) | 298,757 (99) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Neonatal death* | |||||
| yes | 2 (1) | 804 (1) | 3.96 (0.98-15.97 | 4.23 (1.04-17.29 | 2.43 (0.33-17.65) |
| no | 188 (99) | 299,156 (99) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Infant/child death since time of birth** | |||||
| yes | 8 (4) | 2130 (1) | 6.12 (3.01-12.44) | 5.38 (2.50-11.58) | 4.46 (1.80-11.00) |
| no | 183 (96) | 297,886 (99) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
| Cesarean Delivery | |||||
| yes | 92 (48) | 115,060 (38) | 1.51 (1.14-2.01) | 1.44 (1.07-1.94) | 1.31 (0.96-1.81) |
| no | 98 (52) | 185,148 (62) | 1.0 (ref) | 1.0 (ref) | 1.0 (ref) |
1 Adjusted for maternal age (<18, 18-39, ≥ 40), maternal race, maternal ethnicity, maternal education, maternal marital status, plurality (y/n), infant sex, tobacco use during pregnancy (y/n), alcohol use during pregnancy (y/n), previous preterm delivery (y/n), previous poor pregnancy outcome (y/n), pre-gestational diabetes (y/n). Depending on outcome variable, between 6582-7318 records were excluded due to missing data for 1 or more variables.
2 Adjusted for same variables in model 1, with additional adjustment for pre-pregnancy BMI (4 categories: underweight, normal, overweight, obese). Depending on outcome variable, between 26,675-27,176 records were excluded due to missing data for 1 or more variables.
* Infant non-living at time birth certificate was submitted.
** Infant/child died within 5 years of live birth