Table 2.

Overview of the study area expansion to cover all areas in Fukushima Prefecture

	Initial plan	Plan from October 2012 after expansion of the study area
Study areas	10 local municipalities (2 Cities, 6 Towns, 2 Villages)	59 local municipalities (13 Cities, 31 Towns, 15 Villages)
Cooperating medical institutions	19 institutions	52 institutions (incl.1 in Ibaraki)＊
Target number of participants	6,900	15,900 (increased by 9,000)
Recruitment period	January, 2011 to March, 2014 (3 years)	October, 2012 to March, 2014 (18 months)

＊ Out of about 60 medical institutions with obstetrics and gynecology department within Fukushima Prefecture, 51 took part in the JECS. A portion of the pregnant women who live in the Ken-nan district visited the cooperating medical institution in Ibaraki.