Cho K, et al. - Researchers here aimed to explore whether an association exists between small crown-rump length (CRL) and adverse obstetrical outcomes in pregnancies conceived by IVF and to compare a CRL reference based on IVF pregnancies to a reference based on spontaneous pregnancies. They observed a strong correlation of small CRL in IVF pregnancy with miscarriage, especially in the context of advanced maternal age. No association of small CRL was observed with preterm birth or low birth weight. In this study, a CRL reference based on IVF pregnancies was equivalent to the standard reference for predicting miscarriage.