Background: To investigate the impact of the Great East Japan Earthquake on preschool children's physical growth in the disaster-affected areas, the three medical universities in Iwate, Miyagi, and Fukushima Prefectures conducted a health examination survey on early childhood physical growth.

Methods: The survey was conducted over a 3-year period to acquire data on children who were born in different years. Our targets were as follows: 1) children who were born between March 1, 2007 and August 31, 2007 and experienced the disaster at 43–48 months of age, 2) children who were born between March 1, 2009 and August 31, 2009 and experienced the disaster at 19–24 months of age, and 3) children who were born between June 1, 2010 and April 30, 2011 and were under 10 months of age or not born yet when the disaster occurred.We collected their health examination data from local governments in Iwate, Miyagi, and Fukushima Prefectures. We also collected data from Aomori, Akita, and Yamagata Prefectures to use as a control group. The survey items included birth information, anthropometric measurements, and methods of nutrition during infancy.

Results: Eighty municipalities from Iwate, Miyagi, and Fukushima Prefectures and 21 from the control prefectures participated in the survey. As a result, we established three retrospective cohorts consisting of 13,886, 15,474, and 32,202 preschool children.

Conclusions: The large datasets acquired for the present survey will provide valuable epidemiological evidence that should shed light on preschool children's physical growth in relation to the disaster.