Understanding Society User Support

Hiya,

I'd like to generate a variable that is whether or not an individual is childless (or has had a child) ideally inside or outside the household. I'd really like the variable to be for both USoc/ BHPS. I know that there is a variable in the xwavedat: anychild_dv Ever had a (biological) child - that uses first child's DOB: ch1by_dv First (biological) child birth year
. However given this is part of the xwavedat dataset I wouldn't, for example, be able to use it plot the % of women who are childless as a time series across BHPS and USoc. Would be very grateful for some advice or code that would enable me to construct such a variable that can be used across the two surveys.

Thanks v much in advance,
Charlie