NSFG_data_everypreg: Subset of the 2015-2017 National Survey of Family Growth (NSFG): all live births per respondent.
Description
Same as `NSFG_data` but using *every* birth, not just the *first* birth,
out of the initial subset there
(live births with gestational age < 45 weeks
for mothers aged 20 to 40 at time of conception).