The article by Gladen and Rogan that reports a negative relationship between breast milk dichlorodiphenyl dichloroethene (DDE) levels and breastfeeding duration highlights the importance of context in infant feeding research. Using an outdated reference, the authors claim that breast-feeding duration has been declining worldwide. However, a recent comparison of Demographic and Health Survey (DHS) data collected during the middle and late 1980s and World Fertility Survey (WFS) data collected during the middle and late 1970s shows that breast-feeding duration has increased in 9 out of 14 developing countries.3 In Mexico, these current status data show that the duration of any breast-feeding increased from 11.9 to 13.1 months in rural areas, and from 5.4 to 5.8 months in urban areas over this time period.
