There is no risk of infant botulism from a pregnant women eating honey.
Infant botulism results when an infant eats honey or some other food
which contains Clostridium botulinum bacteria.  The infant has a low
stomach acidity and thus the C. botulinum cells can survive and grow
in the intestinal tract, producing the botulism toxin. (Infants can
also obtain the C. botulinum cells from dust in the house.)
 
In adults, botulism is caused by eating a food which contains the toxin.
In infants, the bacteria actually grow and produce the toxin in the
intestine.
 
Val Hillers
Extension Food Specialist
Washington State University