Cohort Profile: The Birhan Health and Demographic Surveillance System

The Birhan health and demographic surveillance system (HDSS) was established to determine the magnitude and causes of morbidity and mortality in Ethiopia among pregnant and postpartum women and children. Located in the North Shewa Zone of the Amhara Region, the site includes 16 kebeles (villages) and spans two woredas (districts), Angolela Tera and Kewet/Shewa Robit. The initial census was conducted in May 2018, and core demographic and health events are updated every three months. The site has 18,933 households and a population of 77,766. Over 82.6% of the population is rural. During the baseline census, all households were geocoded; household members were enumerated; and data were collected on sociodemographic status, housing construction material, economics and asset ownership, care seeking behaviors, and water and sanitation access. During each subsequent round, data on key demographic events such as births, deaths, marital status changes, in-migration, or out-migration were collected for all enumerated household members. Pregnancy surveillance was conducted among married women of reproductive age 15-49 using a pregnancy screening questionnaire and confirmed by urine pregnancy tests. Morbidity and immunization status data for children aged under two years were collected during each round.