In Reply.—

Dr Ryan is correct that readers should be aware of a number of key differences between the National Immunization Survey (NIS) and the Ross Laboratories Mother Survey (RMS) to make direct comparisons between the 2 surveys. Each survey has its own pros and cons that readers need to consider when they interpret the data.

The major strength of RMS is that it is the largest survey of breastfeeding in the United States, whereas the major strength of NIS is that it has a much higher response rate than RMS (75% vs 28%).1,2  It is true that the sample size of the 2002 NIS is too small to provide breastfeeding rates at the state level, because only ∼13% of NIS respondents were asked about breastfeeding questions. The good news is that since January 2003, the breastfeeding questions have been asked of all NIS survey respondents...

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