Background There is no accepted and widely used indicator for exclusive breastfeeding since birth. Indeed, the difference between ‘current status’ data on exclusive breastfeeding and data on ‘exclusive breastfeeding since birth’ is rarely recognized. We used data from a longitudinal study to examine this issue.

Methods A descriptive longitudinal, prospective study design was used in which 506 mother-infant pairs were included. The mothers completed daily recordings on infant feeding during the first nine months after birth. A research assistant conducted fortnightly home visits with structured interviews. The resulting data on breastfeeding patterns are presented in two different ways: analysis of ‘current status’ data based on a single 24-hour recording of infant feeding at 2, 4 and 6 months of age, and analysis of data ‘since birth’, i.e. data on infant feeding for every day, starting from birth until the ages of 2, 4 and 6 months.

Results A wide discrepancy between the results obtained from the two analyses was found. The difference in the exclusive breastfeeding rate was over 40 percentage points at both 2 and 4 months of age (92% versus 51% at 2 months and 73% versus 30% at 4 months) and 9 percentage points at 6 months (11% versus 1.8%).

Conclusions Current status indicators based on a 24-hour period may be inadequate and even misleading for many purposes. We propose that in many studies an indicator called ‘exclusive breastfeeding since birth’ could be added.