In captivity the mating method for guinea pigs can be carefully carried out.  The owner can either leave a boar (male) with ten females for mating or they can use a single sow (female) if they want a particular female to be bred.  The female has an estrus cycle which is the time it takes for her sexual arousal to commence and end.  It lasts around 13-17 days.  The actual mating occurs some days into the cycle when the female is at her estrus peak.

If you choose to breed guinea pigs, the female should be bred when they are older than three months but no later than six months for her first litter.  If any earlier, or later, she may have difficulty during the birthing process.  The male guinea pig should be about five or six months old before he is allowed to breed.  It is important to breed these creatures when they are physically mature; otherwise there is an increase possibility of producing weak offspring, as well as stunting the growth maturity of the female in particular. 

The owner should leave the sow and boar together for only a limited time if mating is seen.  The sow should be taken away from the boar and put into her own cage before birth because right after birth the sow has another estrus cycle and the boar may try to mate with her again. In doing so, the newborns may be trampled by the excitement that comes along with mating.

The gestation period of a guinea pig is normally 68 days but may have a range of 56-74 days.

A litter size averages 2 to 4 babies, but as many as 13 have been recorded! Large litters usually result in death because the mother only has two nipples to feed the young.

Guinea pigs are born fully furred with their eyes open and they are able to run around in a few minutes.  The adorable creatures are also able to nibble at solid foods within 24-36 hours.

A female guinea pig is fertile until she is around three years old.  Males will remain fertile for a longer period, but litter size may be reduced as he grows older.

Nutrition is also a very important factor to a healthy pregnancy. Make sure to read all about the wonders of a guinea pig's diet!