Mouse Gestation Period – How Long are Mice Pregnant For?

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Pet mice are rather effective animals when it comes to their reproduction rate. A female mouse can give birth to a litter of babies approximately every 25 days.

A litter simply means when an animal gives birth to not only one baby, but at least a handful of them.

Every time a female mouse gives birth, a litter of newborn babies come into our world. Mice are pregnant for an average of three weeks (19-21 days).

How to Care for Pregnant Mouse?

In fact, there is not a lot of things you need to do if you notice that your mouse is pregnant. First off, you need to feed her a bit more food because being pregnant consumes a lot of her energy. She is also going to drink more water than her usual daily amount.

Another important thing is to keep the cage at a spot that is not noisy in your house. If you have little children who play a lot throughout the day, then the children’s room is a really bad spot for a pregnant mouse. She has to spend time in a calm environment and gain some extra calories until she gives birth.

If a large part of your house is noisy, then you might need to take that cage to the basement. In case people or other pets constantly go near the cage or the environment is noisy, the female will feel threatened. This is important before giving birth and after it too because a threatened mom might eat her babies.

How to Care for Baby Mice?

There is no need to care for baby mice separately. All you need to do is to take care of their mom. The first thing you need to do is to clean the cage right before the female gives birth. It takes 19 to 21 days for the mother to give birth to her babies counting from the first day of her pregnancy.

Then, provide enough water and food for the female. In the meanwhile, she is going to take good care of the babies. As a mouse owner, there is nothing you can do to contribute to this process. Touching the babies or bothering the female mouse will only make her feel threatened.

Another thing that can make her feel threatened is a noisy environment or one with too much movement around the cage. When she feels threatened, the stress can cause her to eat her babies. Let her take care of the little guys until they grow up and become adults. This takes about 4 weeks.

How to Tell if a Pet Mouse is Pregnant?

After mating, there is always a leftover white plug that can be seen near the female’s vulva area. This plug is going to be visible for up to 48 hours. When this plug falls off, you can consider it as the first sign that your female mouse is pregnant.

She will also start to prepare for giving birth to her babies. If you notice that she is building a nest, it means that she is going to give birth up to 14 days later. During this time, providing your pet with a big enough nesting box is a great idea.

In case you have missed all these signs, there is the last one that you surely won’t miss. Around day 14, your mouse is going to look like she has swallowed a golf ball. Furthermore, her nipples are going to become significantly bigger.

How Often do Mice Have Babies?

A typical pet mouse can give birth to a litter of babies 5 to 10 times every year. The average lifespan of a pet mouse is 2 years. Therefore, we can conclude that a female can give birth a maximum of 20 times throughout her lifespan.

A litter of baby mice is usually a group of 10 if we average it out. A very active female can give birth 10 times a year, as we mentioned. This means that she can produce up to 100 babies every year or 200 babies in her lifetime.

At What Age Can Female Mice Get Pregnant?

It usually takes a maximum of 8 weeks until a female mouse reaches fertility. From then on, they can give birth to another litter of babies every time 25 days have passed. They can continue doing this until they die or become too old to reproduce.

A female mouse takes care of her babies for 3-4 weeks. Then, you should consider separating them because they are going to hit the 8-week mark before you know it. If you don’t want to end up with a lot of pregnant females, then you better start keeping them in a separate cage.

How Many Offspring do Mice Have in their Lifetime?

Female pet mice are rather productive when it comes to reproduction. In their lifetime, they can give birth to an average of 100 babies. But this is just the average, as there are always some females that can give birth to up to 300 babies before they die.

In case you want to breed them, we recommend you to buy only one pair at first and then see how it goes. Either way, you are going to end up with an insane amount of mice if you take good care of them.

Wrapping Up

It is quite obvious that mice are absolute breeding machines. As a mouse breeder, if you take good care of them, then you are going to witness an exponential growth in their numbers in no time flat. A few months go by and you are going to end up with a huge number of mice.

Breeding them is not hard either, as pet mice are rather hardy rodents. You only need to keep the cage clean and provide them with enough food and water. Of course, buying them a few toys for their amusement is not a bad idea either.

avatar I’m Peter King, writer and editor of this blog. I’m a lifelong animal advocate and volunteer at the Animal Rescue League. On this blog I help people learn about pet mice. As a responsible pet owner, you should learn about your pet’s need before getting it. If you have any question or need help, please leave your comment below.

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