| Rate/100,000 (n) | Rate/100,000 (n) | 95% CI/ | |
| Birth Date | 5 States | Other U.S. | Significance |
| April-November (8 months) | |||
| 2010 | 133.22 (600) | 196.90 (4378) | |
| 2011 | 150.54 (672) | 189.47 (4180) | |
| % Ch. Rate | 13.00% | −3.77% | 0.030 - 0.205 (p < 0.008) |
| April-July (4 months) | |||
| 2010 | 134.61 (297) | 197.93 (2178) | |
| 2011 | 149.22 (331) | 190.36 (2018) | |
| % Ch. Rate | 10.85% | −3.38% | 0.004 - 0.246 (p < 0.05) |
| August-November (4 months) | |||
| 2010 | 131.90 (303) | 195.89 (2200) | |
| 2011 | 151.84 (341) | 193.43 (2162) | |
| % Ch. Rate | 15.12% | −1.26% | −0.006 - 0.230 (p < 0.07) |