Can My Male Or Female Guinea Pig Stop Being Able To Get Pregnant When It's Like 5?

Help!like 3 or 4 years ago my guinea pig had 14 babies ! and we sold a lot of them but now we have 2 males (Snowball And Sampson) And 3 females (Babygirl,Rose,&Cinnamon) And There All Like 4,5,6,7 ? Somethying Like pretty old and I know that after a while guinea pigs cant have babies because there hips fuse ! and i dont want them to die ! so please help !!!!!!1 we haven't got them spayed/neutered !are they able to get pregnant ????