Hi Fiston,
I included 97 in my syntax code to be all inclusive. If you are using the same code for a larger analysis across multiple countries or over time you might have women who have had more than 30 doses of SP (though this is rare). I want to make sure that my code will work if I run it for all countries/situations.

For your second question the variables after the "IF" statement is what is restricting your analysis to only women who have had a live birth in the past two years. If you don't include that you will be looking at all women in the dataset which is why you are getting n=18,827.

This is showing the age distribution of women who have had a live birth in the past two years

And this is showing the age distribution of women who had 2+ doses of IPTp