When you work with datasets like the NSFG, it is important to read the documentation carefully. If you interpret a variable incorrectly, you can generate nonsense results and never realize it. So, before we start coding, I want to make sure you are familiar with the NSFG codebook, which describes every variable.
Follow this link to get to the interactive codebook.
Type "birthweight" in the search field, UNSELECT the checkbox that says "Search variable name only", and press "Search". You should see a list of variables related to birthweight.
Click on "BIRTHWGT_OZ1" and read the documentation of this variable. For your convenience, it is also displayed here:
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