Table 1.
Outcome and mediator indicators and assessment tools
| Variable | Tool | Description |
| Primary outcome | ||
| Toddler Cognitive development | Bayley Scales of Infant and Toddler Development (BSID), 3rd Ed59 Cognitive Score | Direct 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 indices | Mother–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 development | Bayley Scales of Infant and Toddler Development | Direct child assessments. |
| Infant Cognitive development | Bayley Scales of Infant and Toddler Development | Direct child assessments. |
| Mediators | ||
| Home environment for infant development | Infant/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 disorders | Depression 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 receptor | Analyses at an accredited Australian laboratory | Venous blood samples, serum separated and frozen for transport to Australia because technical reliability is not assured in Vietnam. |
| Maternal Hb level | HemoCue 210 | Standardised field measurement. |
| Maternal urinary iodine concentration | Analyses at an accredited Vietnamese laboratory | Urine samples frozen in the field and transported in a cold chain to a national accredited laboratory. |
| Infant Hb level | HemoCue 210 | Standardised field measurement. |