hey dan heres a coupla my girls both preggus,the big one died with 28 bubs in her & the lil one had 13 bubs which id say is roughly avrge.
cheers popp
P.s I rang vets bout bluies having birth problems & was told there was no reported cases,so if your bluie looks like there having a hard time dont hesitate to go to vets cause a csection coulda saved mum & bubs.