Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.
FERTPREFMN (MV602) reports responses to the question, "Would you like to have a (another) child or would you prefer not to have any (more) children"? The standard response categories are "have another," "no more/none," "undecided," and various categories related to not being at risk of having more children (such as sterilization, infecundity, and not having a partner).
In IPUMS-DHS, all responses in the general category of "not at risk of having more children" share a common first digit of 4, while the second digit distinguishes between the specific reasons (for example, code "41" for "Sterilized [respondent or partners]").