C-MaMiE is a population-based cohort which recruited over a thousand pregnant women from the predominantly rural demographic surveillance site in Butajira, south central Ethiopia. The women within the cohort were 15 to 49 years and in their third trimester of pregnancy at time of recruitment. Ten time-point assessments were conducted starting in pregnancy and at 2, 12, 30, 36, 42, 48, 60, 78 and 102 months of age of the child in the postnatal period. When the average age of the C-MaMiE project children was 6.5 years (78 months), the cohort size was augmented by 1,345 children and their mothers (the ‘expanded C-MaMiE cohort’) who were identified by health and demographic surveillance site (HDSS) records as having been born in the 12 months preceding (n = 572) and following (n = 773) the recruitment of the C-MaMiE cohort. A total of 2,090 mother–child dyads were assessed at 6-7 years of age, and 1,957 were assessed at 7-8 years of age.