Gestational age:Time:Pt:^Fetus:Qn:US+Estimated from HC derived.Chitty 1997
gestational age:time:pt:^fetus:qn:us+estimated from hc derived.chitty 1997
Gestational age estimated from Head circumference derived on US by Chitty 1997 method
gestational age estimated from head circumference derived on us by chitty 1997 method