Dr Phil: My 18-month-old is underweight for her age 

When we weigh infants, we compare their weight (and length and head circumference) to a standardised chart. This shows their weight relative to the population at that age. We refer to these as centile charts

At a recent developmental check, the public health nurse said my 18-month-old daughter is slightly underweight for her age but it is no cause for concern. I was shocked — I go to great trouble to ensure she has a good diet. Is there anything I can do to ensure she puts up weight?

A child's weight gain is often a cause for stress and concern for parents but usually less so for health professionals.