There are various ways of measuring infertility from DHS data. For a full discussion of this topic, see DHS Comparative Report No. 9 (Infecundity, Infertility, and Childlessness in Developing Countries), available here http:// dhsprogram.com/publications/publication-CR9-Comparative-Repo rts.cfm. There are also a number of difference ways of calculating son preference from DHS data. One useful resource is DHS Comparative Studies #23 (Gender Preferences for Children), available here http:// dhsprogram.com/publications/publication-CS23-Comparative-Rep orts.cfm. You can find other useful resources by searching for "son preference" on the DHS Program website. http://dhsprogram.com