The MRC National Survey of Health and Development 1946 (NSHD) was the first ever British birth cohort study. It has collected information from birth to the current day on the health and life circumstances of five and a half thousand men and women born during a week in March 1946 throughout England, Wales, and Scotland. The study explores differences in child development by factors like social class, biological factors, health and education. Due to the length of the study it has developed into a study of ageing.