I really liked this article about Mary's pregnancy and delivery.
It is not well-known among Catholics that Jesus was delivered of Mary through a miraculous fashion. Our modernist mentality tends to exclude of divine intervention into natural events. But there you have it, Sacred Tradition has always upheld that Mary did not suffer during labour, nor did birth affect her physical body. It has been said that Jesus was born like a shaft of light.I don't know if this is a metaphor or literally. I tend to take it metaphorically, that it's a symbol conveying the miraculous nature of the delivery rather than the actual mode of birth.