A yukkuri that is currently bearing children. There are two widely accepted methods of pregnancy.
The original method is the stalk type. In this the mother grows a stalk from her forehead and the koyukkuri form on it. Usually the number born this way range from three to five, but exceptions do exist, normally on the lower end. When it's time for them to be born, they simply fall off the stalk. The toughness of the kos vary but the general consensus is that they need a softer landing than hard ground.
The second type is the mammalian_pregnancy, or when the yukkuri carries the babies inside her. Variations on this exist as to how they're held inside. More often than not there are one to two kos via this method, though more are possible. Delivery is done by pushing the baby out the mamumamu.
Neither type has an assured method of causing it anymore, though each one has types of sex that will more often result in that type of birth.
There is also the egg pregnancy, though this is uncommon and mostly seen on house yukkuris / home yukkuris.