Introducing solids before 6 months: Inaccuracy of maternal recall at 1 year

Background: The AAP recommends exclusive breastfeeding for 6 months. Early introduction of solids can interfere with breastfeeding, and is associated with adverse health outcomes like obesity. Many studies use maternal recall to determine when infants start solids. Our goal was to determine accuracy of maternal recall regarding starting solids, at 1 year postpartum. Methods: Between 2008-2010 we telephoned mothers of infants enrolled in a cohort study monthly, for 6 months, and asked if they had given their baby any solids in the past month. The first month a mother answered yes was considered the month solids were started. At 1 year, we asked the same mothers when their child was first given solids. Percent agreement and the kappa statistic (k) were used to measure agreement between responses. Results: We obtained data on 148 women. At one year, 8% (12/148) accurately described the month they first gave solids; however, 90% (133/148) reported starting solids later than they were actually started (k = 0.05) (for example, our monthly records indicated solids were started at 2 months, but at 1 year, the mother recalled starting at 6 months). On average, incorrect responders overestimated by 2.3 months (range 1-8 months); 15.5% (23/148) overestimated by 4 or more months. Conclusion: At 1 year postpartum, only 8% of women accurately recalled when solids were started. Similar errors in breastfeeding studies could compromise the validity of reported health outcomes, especially if women consistently report starting solids later than they were actually started.