Mothers were divided into two groups based on their
body mass index: underweight (BMI18.5) and the rest.
It has been well-established that body mass index is a
reliable indicator of chronic energy deficiency [33]. We
follow the standard practice of defining underweight
women as those whose BMI was less than 18.5 kg per
square metre. It would have been ideal to have measured
this variable during the preconception period to examine its
effect on birth weight of infants. But in the survey the BMI
of mothers was measured at the time of survey which could
be up to a year after the birth of the child included in the
analysis presented here.