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Guinea Pig Life Cycle – Reproduction – Pregnancy – Breeding

This article explains the lifecycle of a guinea pig, covering reproduction, pregnancy, birth, newborn baby guinea pigs, overall lifespan, neutering, and breeding considerations. While breeding guinea pigs is not recommended, understanding these life stages is essential to prevent unintended pregnancies and ensure the well-being of these animals.


Guinea pigs reach adulthood at six months but may continue growing until one year old. Typically, they weigh between 900 and 1200 grams, with males (boars) being heavier than females.

The life expectancy of a guinea pig is usually four to eight years, but some may live up to ten or eleven years. The oldest known guinea pig reached fourteen years.

guinea pig age to human years
Guinea Pig Age to Human Years


Female guinea pigs can become pregnant as early as four weeks old and can give birth to up to five litters a year. Their reproductive cycle lasts 15-17 days, and towards the end of this cycle, there is a brief 6-11 hour window for conception. Unlike some mammals, guinea pigs don’t have periods or bleeding during this cycle. 

Breeding guinea pigs before three months of age is not recommended, as babies from very young mothers tend to be weaker and more vulnerable.

Preventing a guinea pig’s first pregnancy after six months of age is critical. If they have not been pregnant by then, their pelvic bones will have fused by 6-9 months, making natural birth impossible and potentially fatal without a caesarean section.

Male guinea pigs reach sexual maturity between 4 and 8 weeks old, with some displaying mating behaviour as early as two weeks.

Mother And Baby Guinea Pig
Mother and Baby Guinea Pig


Pregnancy in guinea pigs lasts 63 to 72 days or 9 to 10 weeks. Unlike some other animals, they do not build nests during this time.

Signs of Pregnancy

It is common for guinea pig owners not to realise their guinea pig is pregnant until she gives birth. Some of the signs of pregnancy are: 

  • Increased thirst
  • Hair loss on the flanks and back
  • A significant increase in abdominal size, often doubling
  • Increased appetite
  • Being able to feel the movement of babies in the abdomen during the later stages of pregnancy

Care During Pregnancy

Pregnant guinea pigs should receive the same high-quality care as always. Though no particular changes are needed, introducing alfalfa pellets and can be beneficial, as they are richer in protein and calcium.

Mother Guinea Pig With Babies
Mother Guinea Pig With Young Babies

Signs of Guinea Pig Labour

There are very few signs that a guinea pig is about to give birth. However, in the week before labour, the pelvis area in front of the genitalia may widen, reaching approximately an inch wide about an hour before delivery.


Guinea pigs typically have litters of two to four pups, but single births or larger litters of up to ten or eleven are possible.

During birth, a guinea pig squats similarly to when urinating. The first pup should arrive within five minutes, with subsequent deliveries about three to four minutes apart. During these intervals, the sow cleans each newborn and consumes the foetal membranes.

A guinea pig usually delivers all her pups within twenty to thirty minutes. 

The entire birthing process usually lasts 20 to 30 minutes. If labour lasts significantly longer, there might be complications. Inexperienced owners should avoid intervening and contact a veterinarian instead. According to the RSPCA, around 20% of sows die giving birth.

After she has given birth, the mother eats the placenta. This helps with the milk production.

Mother Guinea Pig Nursing Her Babies
Mother Guinea Pig Nursing Her Babies

The sow can get pregnant within two to ten hours after giving birth, with a 60-80% chance of becoming pregnant again if a male mates with her during this period. 

Therefore, separating the male from the female in the late stages of pregnancy is crucial to prevent immediate re-conception.

Baby Guinea Pigs

Baby guinea pigs are called pups. Born with open eyes, teeth, a full coat of hair and strong legs, they resemble miniature adults.

A pup typically weighs around 100 grams at birth, but this can range from 45 to 115 grams. Pups weighing less than 60 grams have a significantly lower survival rate.

Initially, they may appear wet and unsteady, but within a few hours, they become fully mobile and will be popcorning, squeaking, and following their mother. Pups usually do not nurse in the first 12-24 hours, during which the RSPCA advises against disturbing the sow and her young.

Baby guinea pigs start eating hay almost immediately after birth and progress to vegetables, fruits, and pellets within a few days.

Identifying the sex of the pups is easiest shortly after birth, but handling should be avoided until it is safe to do so, following RSPCA guidelines. After this initial period, sexing becomes more challenging until they reach 3-4 weeks old when it gets easier again. 

Male pups should be separated from the mother and female siblings at three weeks of age to prevent early reproductive behaviour, including attempts to mate with their mother.

baby guinea pigs
Baby Guinea Pigs

Female pups can stay with the mother until lactation (milk production) has finished or until the sow decides she no longer wants to nurse. This is usually around four to six weeks. Pups are generally ready to be rehomed at six weeks.

Neutering Guinea Pigs

The RSPCA advises neutering male guinea pigs when they are 3-5 weeks old. Neutering males is usually preferred, as spaying females involves a more complex surgery. 

However, it’s important to note that a male guinea pig can still impregnate females up to six weeks after their neutering operation. He must be kept separate from female guinea pigs during this time to prevent accidental pregnancies.


Breeding guinea pigs responsibly is challenging and requires much effort and knowledge. If not managed carefully, it can quickly become too much to handle.

Accommodating Different Sexes

Male guinea pigs can live together in pairs if they have enough room, but keeping several males in one space can lead to fights. Since young males must be separated from their mothers early, you must have enough space for everyone.

Mother And Baby Guinea Pigs
Mother Guinea Pig With Her Baby Guinea Pigs

What Will Happen to the Baby Guinea Pigs?

Baby guinea pigs are cute, but thinking about their future is important. Many guinea pigs end up in rescue centres because there are too many of them and not enough homes. 

Rescues often can’t take in all the guinea pigs that need help because they simply don’t have enough resources.

Before you decide to breed, think about where the baby guinea pigs will go. Sometimes, even guinea pigs that find homes are given up later. Unfortunately, some end up neglected or abandoned in places where they can’t survive.

In the UK and many other countries, there’s a big problem with many guinea pigs being abandoned because there aren’t enough resources to care for them. This leads to sad stories of guinea pigs being left in the wild or neglected.

The following news stories illustrate the current problem with overbreeding:

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