International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown–rump length in the first trimester of pregnancy

摘要

ObjectivesThere are no international standards for relating fetal crown–rump length (CRL) to gestational age (GA), and most existing charts have considerable methodological limitations. The INTERGROWTH-21^st Project aimed to produce the first international standards for early fetal size and ultrasound dating of pregnancy based on CRL measurement.