Gestational age:Time:Pt:^Fetus:Qn:US+Estimated from HC.Merz 1988
gestational age:time:pt:^fetus:qn:us+estimated from hc.merz 1988
Gestational age estimated from Head circumference on US by Merz 1988 method
gestational age estimated from head circumference on us by merz 1988 method