Does listening to classical music make my fetus smarter?

Could not hurt! There is no doubt that the fetus can appreciate sounds and may have a hearing sense well in advance of 9 months. Classical music is harmonious and has mathematical elegance, it can therefore enhance fetal neural networking development and lay the ground for reason and good sense.
No. Classical music can be very relaxing and pleasant so if it helps you during your pregnancy, go for it. The fetus is mostly listening to your heartbeat and intestinal motion sounds.