The significance of crown–rump length measurement for predicting adverse pregnancy outcome of threatened abortion

OBJECTIVES: To determine if in women with threatened miscarriage the measurement of fetal crown-rump length (CRL) is a useful predictor of spontaneous miscarriage and small for gestational age (SGA) infants. METHODS: Fetal CRL was measured in 310 singleton pregnancies with live fetuses, presenting with threatened miscarriage before 13 weeks of gestation. The relationship between fetal CRL and pregnancy outcome was investigated. RESULTS: In fetuses with CRL < 18 mm there was a significant positive association between the deficit in CRL for gestation and the incidence of subsequent spontaneous miscarriage. In those cases with CRL deficit more than 2 standard deviations (SDs) the incidence of miscarriage was 13.7%, whereas if the CRL was between the mean and -2 SDs the incidence of miscarriage was 8.3%. In fetuses with CRL > or = 18 mm there was a significant positive association between the deficit in CRL for gestation and the incidence of SGA. In those cases with CRL deficit of more than 2 SD the incidence of SGA was 27.3%, whereas if the CRL was between the mean and -2 SDs the incidence of SGA was 18.9%. CONCLUSIONS: The findings of this study suggest that the measurement of fetal CRL may be a useful predictor of spontaneous miscarriage and SGA in pregnancies with threatened miscarriage.