If no step being taken, one female will give birth to many kitten and then this female kitten then grow up will give birth to many more kitten, you can check this fact on web.
So, please spay/kembiri the female cat in order to prevent more stray kitten. or you can take the stray female to SPCA/PAWS hopefully they will eventually spay/neuter the cat. May God Bless You.