Can my 4 week old guinea pigs get pregnant?

Question
I brought back my guinea pig and her 4 week old babies, 2 girls and a boy. They were in the same cage until today. I saw Pop (the male one) trying to mount his mother (which is what it looked like) and she was running away, it woke me up this morning because the mother guinea pig ran and made a loud bang. I saw him trying to what looked like (get on top of her, or mount her) so i have now separated the male from the females, but i can't be sure he hasn't tried or has mounted the other 2 female baby guinea pigs. They are 5 weeks old tomorrow and i am worried he may have got one or even both pregnant. What are the chances of that?

Please help!

Nadine

Answer
Hi Nadine,

Pop will have reached sexual maturity at around four weeks of age, and so can theoretically have got all three of your girls pregnant, I'm afraid. I would be more concerned about the mother being pregnant than the two young girls - as back-to-back pregnancies are not a good idea. She is of course big enough to have fought him off, as you have witnessed.

You will need to keep Pop on his own from now on. Once he is fully grown, it may be worth introducing a young male to him so he has a companion. Or adopting an older male to pair up with him now (a male who has never been bred from). However, as you may have more babies on the way you will probably want to wait to see if the litter(s) result in any males rather than buying/adopting any extra piggies. Make sure Pop's cage is close to the females so he can still talk to them, otherwise he will get lonely.

It will be too early to tell if the females are pregnant, you will just have to keep a close eye on them. Look out for signs such as weight gain (to the side of the belly), increased eating and increased drinking. Of course, as the young females are growing it will be harder to tell if they are pregnant or simply growing up. Guinea pigs are pregnant for nine to ten weeks, so you will probably know in about seven weeks' time for sure.

Good luck and if you have any other questions, just ask.

Jenny.