This seems like a small sample size to me, but the scientists say it is statistically significant:
The recent CDC Morbidity and Mortality Weekly Report indicates that eight cities in the northwest U.S. (Boise ID, Seattle WA, Portland OR, plus the northern California cities of Santa Cruz, Sacramento, San Francisco, San Jose, and Berkeley) reported the following data on deaths among those younger than one year of age:
4 weeks ending March 19, 2011 – 37 deaths (avg. 9.25 per week)
10 weeks ending May 28, 2011 – 125 deaths (avg.12.50 per week)
This amounts to an increase of 35% (the total for the entire U.S. rose about 2.3%), and is statistically significant. Of further significance is that those dates include the four weeks before and the ten weeks after the Fukushima Nuclear Power Plant disaster. In 2001 the infant mortality was 6.834 per 1000 live births, increasing to 6.845 in 2007. All years from 2002 to 2007 were higher than the 2001 rate.
A story worth following.