They breed very easily pretty much any time. Our male was a very good father and helped to look after the babies. We had no concerns in leaving him in the cage during pregnancy and after the birth. However, as we discovered the female can get pregnant again immediately after giving birth. This caused us to have another baby very soon after the first lot. Obviously this must happen in the wild but we were concerned about the well being of the mother and the babies who were mainly female so we had him snipped. It was either that or keeping them separate. As we decided to keep most of the babies and as they loved being together so much we felt that preventing further pregnancies particularly with the babies was the priority. There are a surprising number of chinchilla web sites which can give good advice on breeding chinchillas.