Gestational age:Time:Pt:^Fetus:Qn:US+Estimated from FL.Obrien 1982
gestational age:time:pt:^fetus:qn:us+estimated from fl.obrien 1982
Gestational age estimated from Femur length on US by Obrien 1982 method
gestational age estimated from femur length on us by obrien 1982 method