Objective: The purpose of this study was to evaluate the association between the crown-rump length (CRL) difference in twin gestations and adverse pregnancy outcome.
Study design: Women with a first trimester ultrasound scan of a twin pregnancy who delivered between June 2000 and March 2006 at Northwestern Memorial Hospital were identified. The association between the difference in CRLs and pregnancy outcomes was explored.
Results: For the 178 twins who were eligible for the study, the median difference in CRLs was 4.2% and the median difference in birthweights was 9.3%. Twins with a CRL difference of >85th percentile (11.1%) were more likely to have discordant birthweights and to have at least 1 of the pair be small-for-gestational age, be admitted to the special care nursery, and have perinatal morbidity.
Conclusion: CRL differences of >85th percentile are associated with several measures of adverse perinatal outcome.