Outcome assessment
Details of outcome assessment have been elaborated on elsewhereTwo independent personnel measured each child, and repeated measurements were taken. Measurements that differed between the two personnel by 7 mm for length or 50 g for weight were taken again. Means of the final pairs were used in further analysis. Inter-rater reliability was high. Length, weight and weight-for-length, BMI and head circumference were converted to age standardised z-scores using INTERGROWTH-21st standards for newborn size, postnatal growth standards for preterm infants to 64 weeks of postmenstrual age (weight, length and head circumference only) or WHO child growth standards, as appropriate