While fetal and neonatal deaths within the first week of life (termed perinatal mortality) have been decreasing in Japan consistently since 2002, data examined in Fukushima-affected areas during 2012-2015 show a break in this trend with an increase that, as of 2015, had not reversed.

This recent study examines numbers of perinatal deaths in areas affected by the ongoing Fukushima nuclear catastrophe and compared these data to other areas of Japan supposedly unaffected.

This research is just the latest showing a perinatal mortality increase following Fukushima. A number of studies in Europe also showed similar increases following the Chernobyl nuclear catastrophe.  

Increases in perinatal mortality in prefectures contaminated by the Fukushima nuclear power plant accident in Japan

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5044925/