Short-term weight variability in infants and toddlers: an observational study.

Aims: To explore short-term weight variability in young children; (1) how it relates to expected weight gain and (2) how it is affected by age, time of day and dietary intakes and outputs.

Methods: Twenty healthy infants aged 2-10 months and 21 healthy toddlers aged 12-35 months were weighed at home by their parents six times over 3 days. The toddlers' parents also recorded whether they had eaten, drunk, urinated or passed stool in the previous 2 hours.

Assessing the optimal time interval between growth measurements using a combined data set of weights and heights from 5948 infants.

Background: Current guidance on the optimum interval between measurements in infancy is not evidence based. We used routine data to explore how measurement error and short-term variation ('noise') might affect interpretation of infant weight and length gain ('signal') over different time intervals.

Method: Using a database of weights and lengths from 5948 infants aged 0-12 months, all pairs of measurements per child 2, 4 and 8 weeks apart were extracted.