too few baby mice in litter?

Question
Hi my daughters mouse had only 2 babies, this is her first litter and she is 9/10 months old, is this normal as she was quite big. She seems well in herself and is caring for her young which are now 4 days old.

Answer
Dear Claire,

I had a mouse once who produced a litter every third Sunday.  She had any number imaginable in her litters, up to 18 and down to one, fat and happy baby.  The fewer babies there are, the more milk and attention they get.  So it is very possible that she was simply pregnant with two babies.

It is also possible that there was something wrong with some other newborn pups and she ate them.  This sounds gross, but it does recycle the energy from the defective mice into energy for the healthy ones.  Also, a  first time mother gets confused sometimes and does this even with healthy babies.  Confusion can also arise from some kind of stress such as being moved or loud noises.

I think your mouse will have more pups next time.  If she doesn't, not being a mouse gynecologist I can only guess that she has a problem with some of her wombs.  Mice actually have one womb per pup-- they are strung out like Christmas tree lights.

Have fun with the little mice!  Don't forget to separate them at 4 1/2 weeks so you don't end up with hundreds of mice!

squeaks n giggles,

Natasha