Pet Gestation Periods | The Pet Encyclopedia

Kittens Nursing Nursing Kittens (cc)

So, it looks like your beloved pet may be a mommy soon, but you aren't sure when to start preparing for the babies. If you have a small mammal under your care, it's important to know when she will be expecting her little ones so you will have everything ready. Here are the average gestation periods and litter sizes for common house pets, to help you get the nursery ready for their arrival.


Dogs typically have a gestation period of nine weeks, or 63 days. Depending upon the breed, dog litter sizes may range from only one puppy to a dozen. It's important to research your dog's particular breed to see how many little ones you should prepare for.


The gestation period for most cat breeds is anywhere from 62 to 67 days, with 64 days being the average. Again, depending upon breed, cats may have anywhere from one to a dozen kittens in a litter, so it's important to be prepared for what may greet you at birthing time.


A gerbil's gestation period is between 22 and 27 days. Most gerbils will have three to seven babies per litter.


The hamster has the shortest gestation period of all animals that are considered to be mammals. The hamsters gestation period is only 16 days, just a little over two weeks. Hamsters typically have two to 20 babies per litter.


The ferret has a little longer gestation period, just between 40 and 44 days. The ferret also has smaller litter sizes, with three to four babies per litter.


The common pet mouse has a gestation period of about 21 days. A mouse's litter will yield three to twelve babies.


The typical pet rat has a gestation period of 21-28 days. Each litter will produce four to seven babies.

Guinea Pig

The guinea pig also has a little longer gestation period. Guinea pigs are usually born between 59 and 72 days gestation, and the average litter size is three, but can produce up to six.


Pet rabbits have a gestation period of about 28 days. Each litter yields two to four baby bunnies.

Domesticated Birds

Gestation periods are wildly different for birds, and the exact amount of time needed for an egg to hatch depends upon the type of bird. You can expect your baby birds to hatch anywhere between 10 and 75 days. As you can see, this is a huge disparity, so it's important to do the research on your particular bird so you can see what you are dealing with.

Freshwater Fish

This is another animal that has wildly varying gestation periods, depending upon the type of fish. The average gestation period for freshwater fish is about 28 days, but can vary a week in either direction depending upon the breed.

Small Reptiles

Again, this is based upon the type and breed of reptile that you are dealing with. Gestation periods for most pet reptiles can be anywhere from two weeks to 65 days, so check with an expert for your type of reptile.