Infectious diseases, chronic diseases, and mental disorders in both adults and children are reported after disasters occur. The correlation between chronic diseases and mental disorders has also been reported. Moreover, disasters may affect perinatal outcomes. Thus, both adult and child health should be carefully monitored in disaster aftermath. A prospective cohort study of pregnant women and their families, the Tohoku Medical Megabank Project (TMM) Birth and Three-Generation Cohort Study (TMM BirThree Cohort Study), has been conducted since 2013. A total of 73,529 family members participated in the TMM BirThree Cohort Study. Among siblings, the proportion of "small for gestational age" was the same in the pre-and post-disaster periods. Among parents and grandparents who answered the baseline questionnaire, 5.6% in the inland area and 19.8% in the coastal area had their houses totally/mostly destroyed by the Great East Japan Earthquake. Although a depression trend due to house damage was not observed in mothers, the proportion of psychological distress was high according to house damage (P for trend = 0.04). Among parents, there was an increase in overweight persons (P for trend = 0.004 in mothers and < 0.0001 in fathers) and in the number of smokers based on the severity of house damage (P for trend = 0.002 in mothers and < 0.0001 in fathers), whereas no such trend was observed in grandparents. Continuous monitoring and support for those who need are essential. Moreover, utilizing existing cohort studies to investigate health status when we face a new disaster is desirable.