The decreased cerebellar biometry during second and third trimester ultrasound examination is the main parameter to diagnoses cerebellar and pontocerebellar hypoplasia. Investigators already described that a transverse cerebellar diameter (TCD) below the 5th centile at second or third trimester scan is related to a high rate of fetal malformations, severe intrauterine restriction in growth, chromosomal anomalies and genetic disorders, therefore when facing a TCD below the 5th centile, patients should be referred for oriented sonogram, fetal MRI (Magnetic resonance imaging) and fetal karyotyping.

However, prenatal counseling in case of an isolated decreased cerebellar biometry remains challenging since there are no data in the literature regarding the neurodevelopmental outcome of these newborns. The aim of this work is to evaluate the neurodevelopmental outcome of newborns with a prenatal isolated decreased cerebellar biometry, in order to improve prenatal counseling.

Inclusion Criteria:

• 2nd or the 3rd trimester ultrasound examination realized at the hospital "Femme Mère Enfant" in Lyon between 2008 and 2015
• Isolated Transverse cerebellar diameter <5th centile
• Parents who received the information and did not object to participate to the study

Exclusion Criteria:

• Decreased Transverse cerebellar diameter with associated malformations diagnosed during prenatal period
• Family history of neurodevelopmental delay or cognitive impairment
• Preterm delivery (< 28 WG)
• Severe restriction in growth at birth (<3e centile)
• Neonatal asphyxia (pH blood cord < 7)
• Apgar score < 7 at 5 min of live with transfer to the neonatal intensive care unit

Parents of newborns who have an isolated transverse cerebellar diameter < 5th centile during the 2nd or the 3rd trimester ultrasound examination realized at the hospital Femme Mère Enfant in Lyon between 2008 and 2015.