Little guinea pigs are the cutest critters, and they grow up quickly. However, knowing how many little guinea pigs you’re going to have is a challenge. During pregnancy, determining the litter sizes of a guinea pig is difficult. If you’re looking for a precise number, it’s best to see if your vet can get a clear ultrasound image.
Determining the Number of Pups
Determining the pup number is imprecise, but you can get a rough idea in the last few weeks of a guinea pig pregnancy. You’ll be able to observe how big your guinea pig is getting and how much weight she’s gained. Just remember to be careful and support the guinea pig when handling her.
You can also observe your pregnant guinea pig and touch her. In the least week or so, you’ll see her sides start jumping significantly as the little ones kick. You’ll also be feeling the small balls of guinea pig pup as different lumps in her sides. You can get a rough count this way.

Why It’s Hard to Predict a Litter
Predicting guinea pig litter sizes is difficult on account of how the guinea pig uterus is structured. There are two “horns” in it, each with a varied number of implantation points. All or none of the points on a horn may be used during a given pregnancy.
Numbers on Guinea Pig Litter Sizes
Guinea pigs average anywhere between two and seven pups in a litter. However, the larger recorded litters go up into the lower teens. That was one very pregnant guinea pig, who was probably very happy once birth was over.
Three or four is the most common size for a litter. Your pregnant guinea pig will gain the bell shape no matter how many are in her litter. However, the degree of the bell will change, and she will acquire the pregnancy waddle.
Stillbirths
Stillbirths do occur for guinea pigs, and you probably will not get any warning if that happens. Most guinea pigs can deliver their stillbirths without complications. You should remove stillbirths once your guinea pig has finished birthing all the pups.