Determination of gestational age in twin pregnancy: Which fetal crown-rump length should be used?

Aim: For twin pregnancy, discrepancies in the crown-rump length (CRL) between two fetuses often exist. Evidence is lacking regarding which fetal CRL should be used for estimation of gestational age (GA). Our aim was to determine whether the larger, smaller or the mean CRL is more accurate in determining the GA in the first trimester of pregnancy.