Disruptions in the supply of allopregnanolone, a hormone created by the placenta late in pregnancy, to the developing fetus can leave children more vulnerable to brain injuries associated with ASD. Losing the supply of ALLO alters cerebellar development, an area of the brain critical for motor coordination and social cognition, impacting the post-birth development of cerebellar white matter. An experimental model revealed deficient cerebellar white matter resulted in social impairments and an increase in repetitive behaviors, two hallmark features associated with autism.