Pregnant Mouse 2nd Litter

Question
Hi, my mouse Metal Petal (which my son named) is expecting her second litter (her first are just over 4 weeks old).  I didn't realise she could fall pregnant so quickly but I've since learnt this.  The father unfortunately died so I want have this problem again.  I also separated the boy mice from the girl mice. I'm also now aware of the stress it can put on the mother to have two litters back to back (which I'm sorry about). From Metal Petal's first litter I've kept four girls I am giving one pair away and keeping one pair.  My questions is:- the mother and her daughters are currently sharing one cage, however the mother is due to deliver any day now - should I separate her from her first litter or is it ok for them to stay together.  Your help in this matter would be greatly appreciated.

Answer
Dear Najette,

I'm so sorry about Dad mouse.

You can keep all the girls together.  As many girl mice can live together as can fit happily in a cage.  Your mouse is actually lucky to have had an extra week-- they can mate the same day as the birth, spacing the litters out by only 21 days!!  I'm not sure if 4 week old mice have maternal instincts yet, but older mice help take care of the babies, relieving some of the pressure on the mom.

Squeaks n giggles,

Natasha