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Guinea Pig Pregnancy Calculator

Enter a breeding or conception date to see the published gestation window (59 to 72 days, average 68), the day count and the stage from published sources.

Select the date your guinea pigs mated, or an estimated conception date. Both modes use the same published 59 to 72 day range, counted from the date you enter.

Educational estimates only, from Merck and a peer-reviewed review. This tool does not diagnose pregnancy. Contact a licensed veterinarian.

What This Tool Estimates

  • Earliest, average, and latest due dates
  • Current day and week of pregnancy
  • A 4-stage timeline using published days
  • Current stage from published sources

Gestation range: 59-72 days  ·  Average: 68 days

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Quick Answer

The Merck Veterinary Manual gives guinea pig gestation as 59 to 72 days with an average of 68 days. This tool adds those figures to the date you enter. Breeding on March 1 gives a window of April 29 to May 12, with May 8 as the average. Only a veterinarian can confirm a pregnancy, and the sources do not say which date the count starts from.

The Basics

How This Tool Works

Enter the date your guinea pigs mated, or an estimated conception date, to see the published gestation window.

  1. You enter a breeding or conception date. Both modes use the same figures.
  2. The tool adds 59, 68 and 72 days to that date to give an earliest, average and latest date.
  3. It shows how many days have passed and which of four stages (built from published days) applies, with a prompt to contact a veterinarian.
The Sources

Guinea Pig Pregnancy: What Veterinary Sources Say

Every figure below comes from the Merck Veterinary Manual or the peer-reviewed review Biology and Diseases of Guinea Pigs. Where they differ, both are shown. Always contact a licensed veterinarian about your guinea pig.

Length of Pregnancy

Merck gives 59 to 72 days with an average of 68 days. The review says gestation length is generally inversely proportional to litter size. Neither source says which date the count starts from, so this tool counts from the date you enter.

Litter and Pups

Merck gives an average litter of 2 to 4 pups and the review gives 2 to 5. Pups are born with hair, teeth and open eyes and begin to eat and drink within hours. The review links litters of 3 or more with a higher incidence of stillbirths.

First Litters and Difficult Births

The review says the pubic symphysis fuses between 6 and 9 months of age and that females giving birth for the first time after it fuses are prone to dystocia (difficult birth). Dystocia can also occur in obese sows and sows with large fetuses. Merck says C-sections are risky and have a poor survival rate for the mother. Ask a veterinarian before breeding.

After the Birth

The review says a fertile postpartum estrus occurs 2 to 10 hours after birth, and Merck's advice is to keep opposite-sex guinea pigs apart. Merck gives weaning at 3 to 5 weeks and the review gives 14 to 28 days. Merck gives sexual maturity at about 2 months for females and 3 months for males. Ask your veterinarian when to separate pups.

Safety

When To Contact a Veterinarian

This tool gives dates only. It cannot tell you whether a guinea pig is pregnant or healthy. Contact a licensed exotic-animal veterinarian:

  • ● To confirm a pregnancy. A veterinarian can detect one from about day 15 to 19.
  • ● Before breeding. First litters after the pubic symphysis fuses, and obesity, raise the risk of a difficult birth.
  • ● At any change in appetite, energy or behaviour during the last two weeks of pregnancy or after the birth.
  • ● If the birth is taking longer than expected, or the date you entered has passed the 72-day mark.
  • ● For diet and housing during pregnancy. Merck gives a higher vitamin C figure for pregnant guinea pigs; see the Vitamin C Calculator, and ask your veterinarian about the rest.

Pregnancy Toxemia Warning

The review Biology and Diseases of Guinea Pigs says pregnancy toxemia occurs in late pregnancy (the last 2 weeks) and immediately after birth. It occurs more often in obese, stressed sows with a large number of pups, but normal sows can be affected. Affected animals may die without clinical signs, or may be dehydrated, depressed, anorexic and underweight.

Contact a licensed exotic-animal veterinarian straight away if you have any concern about a pregnant or recently delivered guinea pig. Do not wait to see whether it passes.

Methodology

How Results Are Estimated

The estimate adds Merck's published gestation range to the date you enter. The stage descriptions use only days and facts stated in the Merck Veterinary Manual or the review Biology and Diseases of Guinea Pigs.

The sources do not say whether the count starts from mating, ovulation or another date, so the tool counts from the date you enter. The review says gestation length is generally inversely proportional to litter size. The day 54 boundary is 14 days before day 68, our own arithmetic from the review's 'last 2 weeks' statement.

Earliest = date + 59 days Average = date + 68 days (Merck) Latest = date + 72 days Stages: day 1-14 (implantation on day 6 or 7), day 15-53 (veterinary detection from day 15 to 19), day 54-58 (last two weeks before the average date), day 59-72 (published birth window)

Important Limitations

This tool provides an estimate, not a diagnosis. Keep these limitations in mind when reading your result:

  • This is a date-based estimate, not a pregnancy confirmation. It cannot tell you whether a guinea pig is pregnant.
  • The sources do not say which date their gestation figures count from, so the dates may be off by days.
  • Litter size affects gestation length, and the tool does not know your guinea pig's litter size.
  • Pregnancy toxemia occurs in the last 2 weeks of pregnancy and immediately after birth, and the tool cannot detect it. Contact a licensed exotic-animal veterinarian about any concern.
  • If no birth has happened by day 72, or you have any concern, contact a licensed veterinarian rather than relying on this estimate.
Worked Example

Example Calculation

How the date window is worked out for a guinea pig bred on March 1.

  1. Starting point: March 1.
  2. Earliest: March 1 + 59 days = April 29.
  3. Average: March 1 + 68 days = May 8.
  4. Latest: March 1 + 72 days = May 12.
Example result: a window of April 29 to May 12 with May 8 as the average. Only a veterinarian can confirm a pregnancy.
FAQs

Frequently Asked Questions

The Merck Veterinary Manual gives a guinea pig gestation of 59 to 72 days, with an average of 68 days. The review Biology and Diseases of Guinea Pigs says gestation length is generally inversely proportional to litter size. Neither source says which date the count starts from, so this calculator counts from the date you enter. Only your veterinarian can assess your guinea pig's pregnancy.

Merck gives an average litter of 2 to 4 pups and the review gives 2 to 5. Pups are born with hair, teeth and open eyes, are fully mobile, and begin to eat and drink within hours of birth. The review links litters of 3 or more with a higher incidence of stillbirths.

Only a veterinarian can confirm it. The review says a veterinarian can feel uterine swellings by gentle palpation from about day 15, that ultrasound shows fluid-filled swellings at day 16, and that diagnosis approaches 100% on day 19. It says abdominal distension becomes evident in late pregnancy. Do not try to feel the abdomen yourself. Contact a licensed exotic-animal veterinarian.

No source we checked gives a pregnancy diet, so this page does not give one. Merck gives a higher vitamin C figure for pregnant guinea pigs than for adults in normal health; the Vitamin C Calculator shows it. Ask your veterinarian what to feed a pregnant guinea pig, and do not add vitamin products to food or water without asking.

The review says a fertile postpartum estrus occurs 2 to 10 hours after birth, so a female can become pregnant again very soon after giving birth. Merck's advice for preventing dystocia is to keep opposite-sex guinea pigs apart. Ask your veterinarian when and how to separate them.

The review Biology and Diseases of Guinea Pigs says pregnancy toxemia occurs in late pregnancy (the last 2 weeks) and immediately after birth. It occurs more often in obese, stressed sows with a large number of pups, but normal sows can be affected. Affected animals may die without clinical signs, or may be dehydrated, depressed, anorexic and underweight. Contact a licensed exotic-animal veterinarian straight away if you have any concern.

Breeding carries risks, so ask a veterinarian first. The review says the pubic symphysis fuses between 6 and 9 months of age and that females giving birth for the first time after it fuses are prone to dystocia (difficult birth). Dystocia can also occur in obese sows and sows with large fetuses. Merck says C-sections are risky and have a poor survival rate for the mother.

The review says pups are born every 3 to 7 minutes and delivery is complete in about 30 minutes. If the birth seems to be taking longer, or you have any concern, contact a licensed exotic-animal veterinarian.

The sources differ. Merck gives weaning at 3 to 5 weeks and the review gives 14 to 28 days. Merck gives sexual maturity at about 2 months for females and 3 months for males. Ask your veterinarian when to separate pups from their mother and from each other.

72 days is the end of the published range. Either the date you entered may be wrong or your guinea pig may not be pregnant. Contact a licensed veterinarian.
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References

General public resources referenced while researching this tool's topic.

Editorial Note

This tool is part of PetNurture's educational library. Its formulas and guidance draw on publicly available educational resources, recognised veterinary organisations, and established animal welfare references where appropriate — see the References section below for the specific sources used on this page.

It is provided for general educational purposes and is not a substitute for advice, diagnosis, or treatment from a qualified veterinarian.

Educational Use Notice

Last updated: May 2026

The information provided by this tool is for general educational and informational purposes only. Results are estimates, not a diagnosis, and may vary based on your pet's breed, age, health conditions, activity level, diet, and individual factors.

PetNurture does not provide veterinary, medical, or emergency care advice. Always consult a licensed veterinarian or qualified pet care professional regarding your pet's specific health, nutrition, or medical needs.

While we strive to keep calculations accurate and up to date, PetNurture makes no guarantees regarding completeness, reliability, or accuracy. Use this tool at your own discretion.

How we calculate results: This tool uses commonly referenced veterinary formulas, feeding guidelines, and breed-size estimates to provide general educational guidance. Individual pets may have different nutritional, behavioral, or medical needs that are not captured by any generalized formula.

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AI Overview & Key Facts

  • Purpose: Instant educational due-date estimate to help owners track pregnancy timing and milestones.
  • Input Parameters: Breeding date.
  • Reference Guidelines: Merck Veterinary Manual and the peer-reviewed review Biology and Diseases of Guinea Pigs (gestation 59 to 72 days, average 68).
  • Liability Limitation: Educational estimation only, not a pregnancy diagnosis. Consult a licensed veterinarian for confirmation and monitoring.

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