2 weeks ago I adopted two baby female mice from a breeder. She assured me that they were both female and that they'd been separated from their brothers for a fortnight. Anyway, I noticed they were growing quite quickly and getting quite chubby. It's now apparent that they are in fact both pregnant. One of them is especially heavily pregnant as she is huge. I'm sure she is going to pop any minute. They also both made nests in opposite corners of the tank.

I've been giving them the odd dog biscuit to supplement their food mix. Is there anything else I should do? I'm concerned that they are too young to be giving birth, but it wasn't my choice. Any tips for when the pups arrive?

Thanks in advance.

They are best left alone, especially with first-time mothers or they can cannabalise their young if disturbed.
They are born like little almost-foetuses and they get fur and then open their eyes ~ 10-14 days (at which stage they are particularly adorable). Their ears open a little later.

They come out of the nest ~4/5 weeks of age and you need to sex and separate them at about 6-9 weeks, to be safe.
Remember the sons will happily mate their mothers as well as their sisters

Plenty of good quality mouse food should be fine for them, with maybe an occasional calcium dog biscuit to nibble on.

To have them make the best possible pets I would start to accustom them to a little gentle handling once they are coming out of the nest.

If you handle mum first you can put her scent on your hands until the babies are used to you, it can also reassure her that the babies don't smell too unfamiliar to her


Good luck with your new family

Make sure you buy another cage for the little male mice for when they are old enough, just so you know you have it.

Don't handle them for the first week or so, and try to keep the room they are in as quiet as possible.

PS That is left alone until they come out of the nest