Understanding Society User Support

Hello Dear Admin,

My name is Ameer Khaleel, and I am a PhD student in Economics at Newcastle University. I am conducting research on the impact of working mothers' childbirth on their wages after childbirth. I am specifically interested in understanding the impact of the first child. I have access to the Understanding Society database and am using the indresp subdata for UKHLS from 2009 to 2022.

My question is how I can identify first-time mothers, as there is no direct variable for this. I am aware of variables like ch1by4 (eldest child's birth year), nchild_dv, ndepchl_dv, and nnewborn, but they contain different content, and considering each of them would lead to a different number of observations.

I would appreciate your help with this matter. At the moment, I have tried to identify first-time mothers using the code (sex == 2 and ch1by4 >= 2009 & ch1by4 <= 2022), but this only shows 244 observations over 14 years. Consequently, I am slightly suspicious that this approach might not be correct or that I may be writing the code incorrectly.

Best regards,
Ameer