The bleeding from a newborn girl's vagina is completely normal, it happens due to hormones being absorbed by the baby while still in the womb.
How long can this bleeding last?
Does it come and go, or does it occur only once for a period of time?
Today morning during diaper change of our 12 day old we have noticed some blood and mucus coming from her vagina, and of course have cleaned it. During next diaper change (2 hours later) there was even more blood - even more than during the first few days after her birth when she also bled. Should we be worried?
Update:
My daughter is almost a year old now and we had no further problems. We've also then consulted with a pediatrician, she said it is rare (the blood appearing, disappearing and appearing again), but it happens. And unless there was a relatively large amount of blood (a major leak instead of a droplet) we sholdn't worry.