Matlab HDSS was established in 1966, following a population census conducted by Cholera Research Laboratory. Since then, the Matlab HDSS has maintained the registration of births, deaths, and migrations, in addition to carrying out periodical censuses. Registration of marital unions and dissolution began in 1975, internal movement in 1982, changes in household headship and household dissolution in 1993. Matlab HDSS field site is situated in Matlab Upazila (sub-district) under Chandpur District in Bangladesh. It is located about 55 km southeast of the capital, Dhaka. Matlab HDSS now covers an area of about 184 square kilometres covering 142 villages.