Table 1

Outcome and mediator indicators and assessment tools

VariableToolDescription
Primary outcome
 Toddler Cognitive developmentBayley Scales of Infant and Toddler Development (BSID), 3rd Ed59 Cognitive ScoreDirect child assessments. We have translated the Bayley Scales of Infant and Toddler Development into Vietnamese, adapted materials where necessary and trained local expert administrators. Reference mean score is 100 (SD=15).
Secondary outcomes
 Infant anthropometric indicesMother–infant scale (Seca 876); portable stadiometers and length boards (ShorrBoard)Infant height-for-age, weight-for-age and weight-for-height z scores will be calculated by WHO methods13 using length and weight based on infant’s age and sex.
 Infant Motor and Social-emotional developmentBayley Scales of Infant and Toddler DevelopmentDirect child assessments.
 Infant Cognitive developmentBayley Scales of Infant and Toddler DevelopmentDirect child assessments.
Mediators
 Home environment for infant developmentInfant/Toddler Home Observation for Measurement of the Environment (HOME) Inventory60 Comprises 45 items assessing quality and quantity of stimulation and support available to a child at home through semistructured observation and parent interview at home.
 Maternal common mental disordersDepression Anxiety and Stress Scale 21 items, Vietnam Validation33 We have validated this scale against gold-standard psychiatrist interviews to detect common mental disorders with high sensitivity and specificity.
 Maternal serum ferritin and transferrin receptorAnalyses at an accredited Australian laboratoryVenous blood samples, serum separated and frozen for transport to Australia because technical reliability is not assured in Vietnam.
 Maternal Hb levelHemoCue 210Standardised field measurement.
 Maternal urinary iodine concentrationAnalyses at an accredited Vietnamese laboratoryUrine samples frozen in the field and transported in a cold chain to a national accredited laboratory.
 Infant Hb levelHemoCue 210Standardised field measurement.