Table 4.
Association of influenza vaccination during pregnancy with the risk of small for gestational age (SGA) among mothers of non-malformed infants, stratified by influenza season
| All | SGA | Unadjusted | Adjusteda | |||||
|---|---|---|---|---|---|---|---|---|
| Influenza vaccination timing | n | % | n | % | OR | [95% CI] | OR | [95% CI] |
| 2006–07 Season | ||||||||
| All | 439 | 100.0 | 42 | 9.6 | ||||
| None | 365 | 83.2 | 39 | 10.7 | ||||
| Anytime during pregnancy | 74 | 16.8 | 3 | 4.1 | 0.35 | [0.11, 1.18] | – | – |
| 2007–08 Season | ||||||||
| All | 589 | 100.0 | 62 | 10.5 | ||||
| None | 482 | 81.8 | 50 | 10.4 | ||||
| Anytime during pregnancy | 107 | 18.2 | 12 | 11.2 | 1.09 | [0.56, 2.13] | 1.40 | [0.63, 3.11] |
| 2008–09 Season | ||||||||
| All | 537 | 100.0 | 66 | 12.3 | ||||
| None | 425 | 79.1 | 55 | 12.9 | ||||
| Anytime during pregnancy | 112 | 20.9 | 11 | 9.8 | 0.73 | [0.37, 1.45] | 1.23 | [0.57, 2.63] |
| 2009–10 Seasonb | ||||||||
| All | 387 | 100.0 | 37 | 9.6 | ||||
| None | 346 | 89.4 | 33 | 9.5 | ||||
| Anytime during pregnancy | 41 | 10.6 | 4 | 9.8 | 1.03 | [0.25, 3.13] | 0.60 | [0.17, 2.04] |
a
Adjusted for propensity score.
b
Represents the unvaccinated and the vaccinated against seasonal influenza only; 385 vaccinated against pandemic H1N1 were excluded from the analysis (including 32 SGA).
OR, odds ratio; CI, confidence interval; and SGA, small for gestational age according to reference birthweight percentiles; ‘ – ’, adjusted results not shown (<4 exposed cases).