Well it is not hogwash at all since research has showed that unborn babies who were exposed to music while in the womb showed a great improvement in their overall mental, sensory, psychological and emotional development, compared to those who weren't exposed to any music, while in the womb.
I have no question whether music can affect the fetus. What I'm wondering about is the type of music that is played to the fetus. The debate about classical music versus pop music or rock music has not been concluded yet.