The transverse cerebellar diameter cannot be used to assess gestational age in the small for gestational age fetus.

The transverse cerebellar diameter was obtained in 44 small for gestational age (SGA) fetuses between 27-42.8 weeks. Twenty-nine of 44 fetuses had antepartum and/or neonatal complications consistent with intrauterine growth retardation. The cerebellar diameter was normal in 12 (27.3%), between 1-2 SDs below the mean for gestational age in six (13.6%), and greater than 2 SDs below the mean in 26 (59.1%). Hence, the transverse cerebellar diameter cannot be used to assess gestational age in those fetuses suspected of being SGA.