Connection between the physical work of Pilates and breathing is helpful throughout pregnancy and is especially important during labor and delivery. 

Everything is moving anteriorly, towards the front of the body. Very important to strengthen the posterior chain to stay out of pain. 

This is very unique to Pilates, it is safe to do throughout and you can modify Pilates for how you are feeling that day. 

Empowers you to let go of ego and do what works for you. You decide what feels good because everyone is different. 

This list is just a scratch on the surface of the benefits for Mom's doing Pilates. My site will go into all this in much greater detail.