Linda,
I suspect the spasms in infants weaned from milk containing phenobarbital
constituted withdrawal from chronic exposure.  I would not think that one time
use would have the same effect.  Many infants of epileptic mothers are exposed
to this medication in maternal milk, with no ill effects.
        My concern in this case would be the mother's ability to care for her
infant while flying if she takes the phenobarbital.  Will she be flying alone?
 As someone who cannot take antihistamines without zoning out, I cannot
imagine caring for an infant on an airplane after ingesting barbiturates!
Catherine Watson Genna, IBCLC  NYC  [log in to unmask]