Objectives: Transverse cerebellar diameter measurements have been established for singleton but not twin pregnancies. In singleton pregnancies controversy exists on whether cerebellar growth is affected by intrauterine growth retardation. We undertook this retrospective study in twin pregnancies to establish a nomogram for the transverse cerebellar diameter in twins and to assess the effect of growth retardation on this measurement.
Study design: A retrospective review was performed on 171 patients with twin pregnancies with reliable dating from 15 to 36 weeks' gestation who had been referred to our antenatal evaluation unit for routine ultrasonographic examination. Of the 342 fetuses, 322 were available for analysis and establishment of a nomogram for the transverse cerebellar diameter. Twenty-four twin, growth-retarded fetuses were analyzed separately.
Results: The transverse cerebellar diameter increased linearly with gestational age (r = 0.94, p < 0.001). Fifteen (63%) of the growth-retarded fetuses had a transverse cerebellar diameter of < or = 5th percentile for gestational age.
Conclusion: We suggest that intrauterine growth retardation may affect cerebellar growth in twins.