This study will be conducted in Rahimyar Khan (RYK) in Punjab Province, Pakistan and follows a longitudinal birth cohort design that will be conducted alongside a community-based, cluster randomized intervention trial in RYK (NCT02130856). In the concurrent intervention trial, approximately 6000 pregnant women and their unborn babies will be enrolled to participate in either the control or intervention arm of the trial; approximately half of the women will be enrolled to the control arm and half will be enrolled to the intervention arm. At the time of enrolment, women in the control arm of the trial will also be asked to participate in the birth cohort study.