“…Even though the attrition rate was not mentioned in almost half of the studies, attrition was described for 63% of all studies. The review identified attrition as occurring due to loss of follow-up or differential attrition occurring among families with reported cases of substantiated maltreatment, those from higher socio-economic disadvantaged backgrounds and among males and indigenous people (particularly among MUSP studies) [4,21,46,82,97,98,101,102]. Other attrition reported was death or early infant loss [47,55,93,96], non-response [47] and emigration [47,55].…”