| 95% CI/ | |||
| Rate/100,000 (n) | Rate/100,000 (n) | Significance | |
| Conceived | 5 States | Other U.S. | |
| December, prior to year below | |||
| 2010 | 143.99 (84) | 186.58 (525) | |
| 2011 | 149.04 (84) | 194.17 (542) | |
| % Ch Rate | 3.51% | 4.07% | |
| November, prior to year below | |||
| 2010 | 119.61 (70) | 187.22 (534) | |
| 2011 | 159.85 (93) | 184.58 (537) | |
| % Ch Rate | 33.64% | −1.41% | −0.024 - 0.478 (p < 0.08) |
| October, prior to year below | |||
| 2010 | 142.05 (81) | 198.30 (558) | |
| 2011 | 129.82 (74) | 176.72 (504) | |
| % Ch Rate | −8.61% | −10.88% | |
| September, prior to year below | |||
| 2010 | 140.38 (77) | 206.69 (570) | |
| 2011 | 168.89 (94) | 190.82 (526) | |
| % Ch Rate | 20.35% | −7.68% | |