Cigarettes smoked per D^1st trimester:NRat:Pt:^Mother:Qn
cigarettes smoked per d^1st trimester:nrat:pt:^mother:qn
Cigarettes smoked per D^1st trimester:NRat:Pt:^Mother:Qn
cigarettes smoked per d^1st trimester:nrat:pt:^mother:qn