• A pregnant guinea pig will exhibit certain signs.Guinea pig image by Warren Millar from Fotolia.com
  
  Guinea pigs are a popular house pet because they are passive and relatively clean animals. Unfortunately, pet stores are often unsure if the guinea pigs they are selling are male or female, which can lead to unwanted pregnancies when the genders are mixed. If you suspect your guinea pig is pregnant, some specific and subtle signs will help you know for sure.
  
  

Lack of Estrus Signs

• If you have been actively trying to breed your guinea pigs, your first clue to pregnancy may be the lack of signs that your guinea pig is in season. A female guinea pig experiences a 16- to 18-day cycle starting at about 3 to 5 weeks after birth. When a guinea pig is in season, she exhibits behaviors such as raising her tail end when she is touched and attempting to mount the other guinea pigs in her cage. If you have attempted breeding and 2 1/2 weeks later your female does not exhibit these behaviors, it is likely she is pregnant, according to veterinarian Cam Day of Petalia.
  
  

Increased Food Consumption

• Just as a pregnant woman increases her food and water intake, so does a pregnant guinea pig. You may notice that you find yourself refilling your guinea pig's food bowl and water bottle more frequently. The food and water intake may as much as double as pregnancy progresses. If you suspect your guinea pig is pregnant, do not restrict food intake, since it could be detrimental to both the pups and the mother.
  
  

Weight Increase

• As the pregnancy progresses, a pregnant guinea pig will gain a consistent amount of weight over the 10-week gestation period. If you suspect your guinea pig is pregnant, begin weighing her regularly, at weekly intervals. According to Animal Hospital-USA, in the last weeks of pregnancy, a pregnant guinea pig tends to have a belly that appears swollen.
  
  

Fetal Movement

• In the last two weeks of pregnancy, you can physically see and feel fetal movement. Observe your guinea pig without touching her, and you will see her belly moving sporadically. This is the movement of the litter inside. Before you can physically see the movement, you can turn her upside down in your lap and gently feel her abdomen. It is possible to feel specific body parts, such as legs and heads, depending on the number of pups in the litter and the gestational age. If you can feel the pups, this is a good sign that she will give birth in the next 1 to 2 weeks.