My shapeshifters all present as male but are in fact hermaphrodites. They possess both male and female organs and reproduce sexually but they don’t have babies. Currently this is due to a curse placed on them thousands of years ago as a result of their war with the Hecates (woods witches), which requires them to use human females as surrogates. Even if the curse is lifted they would not bear children though.
All will be revealed in book two, but I think hermaphrodite shapeshifters hasn’t been taken yet.