think my mouse may be pregnant but im not sure

Question
I've had my mice for a good few months now, I bought them as a set of three 'female'mice but I think that one of them is male. Also the other two mice have in the past week or so gained some weight, not loads but I've noticed it. Also one of the females has become quite aggressive towards me and I've seen her be aggressive to the other mice too(mainly the male), before she would happily sit on my hand and would take treats out of my hand etc but now she won't come near me, if I put my hand in the cage she'll try to attack and bite me which she hasn't done before, as I'm not sure if she's pregnant or not this has quite worried me. She's also been gnawing at anything and everything like no tomorrow which is quite unusual for her as in the past she hasn't really been gnawing on stuff that much. I've also noticed that she makes quite a nice, neat bed out of the shredded tissue material I put in the cage for bedding. Her belly seems to drag across my hand when I hold her and I can see a small bulge which I can't see on the male so Im getting the feeling she's pregnant. If so what should i do when she gives birth, would I still be able to clean out the cage and stuff or would i have to wait a bit?

As these are my first set of pet mice I don't really know what to expect so I really need some advice as I'm getting worried and panicky. I've heard that healthy mice arent meant to make noises that humans can hear much but I always hear mine squeaking and making sneezing sounds every now and again, is there something wrong if they make noises?

Thank you, really appreciate it. Izzy x

Answer
Dear Izzy,

Easy answers. Yes, your mouse is pregnant. And yes, your mice are very sick.

You need to get them all to the vet immediately, before anyone gives birth. The vet must be trained either in "exotics" or "pocket pets." The vet will of course notice that one or both are pregnant, but you might remind them that some antibiotics are not recommended during pregnancy. I know Tetracycline is one- which means I can't give you a home remedy.

You also need to take the male out immediately, because he will mate with the female immediately after birth, and you absolutely do not want any more babies. Breeding mice is not for the beginner, especially because, unlike most animals,  male mice very often each need their own cage or they may kill each other. With two litters you are going to have quite a time finding homes for all of those boys without sacrificing some to snakes or for experiments- which will happen if you advertise them for free.

My advice is... If you don't have your heart set on baby mice, ask the vet to abort one or both litters. I don't know if every vet is capable of this. It will save you a lot of trouble. It is so much better than their fates if you can't find good homes for all of them. With two litters you may get a dozen males or more.

If you do choose to have one or both litters, again, clean the cage immediately. After the babies are born you should not disturb them for seven days. You can pick up the moms when they are out of the nest, but not for long. Baby mice nurse every 30 minutes! These gals will be happy that they can help each other out. Even if one does not have a litter, she will help out with the other.

A lot of people have asked me questions about raising babies, so try searching on here before asking me more questions about it. But do feel free to ask. Search in the search box starting with "natasha mice mouse" and your search terms. Always read the most recent answer.

Have fun with the mice, whether you have babies or not!

Squeaks n giggles,

Natasha