The Lilienfeld textbook shared that by the fifth month of pregnancy infants' auditory systems are developed enough to hear sounds from the mother. This sound of course is muffled, but nevertheless they are learning the vocal rhythms and patterns they hear. This concept is important because it explains why an infant is pre-disposed to a specifc language - they are already hearing the characteristics of that language before birth. Being one of those people who fall into the category of having a difficult time learning a foreign language, I wish my mom had been bilingual.
So if you are wondering if infants are learning before they are born, studies show that the answer is yes. But if you think you are going to give them an advantage in life by playing Mozart as opposed to any other music at this early stage, there is no scientific evidence that reflects this. This concept does make me wonder if infants that are exposed to musical rhythms before they are born are more prone to being able to keep a beat.
If you have 3 minutes, watch this short clip that explains why babies can recognize their mothers native language and other interesting facts about babies and learning. main1421648.shtml
Also, here's a Youtube commercial for prenatal music. Can you see how they are attaching scientific findings such as "unborn babies respond to various rhythmic qualities of music" in their ad?