my guinea pigs pregnancy

Question
Hi, I have a female Himalayan guinea pig called Precious. According to my research she should be 7 weeks pregnant. How can i make sure? Its really important i know because a vet told me that i need to separate her from my male guinea pig 1 week before the birth so that everything goes smoothly.

Answer
If you think she is 7 weeks, now is a good time to separate them. Its better to separate too early than too late. You will begin to feel babies active by holding mommy around 2 weeks before her due date.
Around 70 days, 48hrs before she gives birth, her pelvis bone (between her legs) will spread to an obvious 1.5 inches. From that point on it is close to show time. She will give birth on her own, and involvement by you is a bad idea. The only time you should get involved is if she is screaming or pushing for over 10 minutes without the result of a baby. In these cases she should be rushed to a local vet. Cesarean sections are not healthy and very dangerous.
The babies stay with mommy for 3 weeks.  At this time, mommy, baby girls, and baby boys should be separated from each other. No male should be with a female. In order to sex the babies (which can be done immediately) go to: http://www.cavyspirit.com/sexing.htm  
The baby boys are sexually mature at age 3weeks, so they are able to get mommy or sissy pregnant, so separation is important. They should stay in your care for another 3-4 weeks before finding a home.
Mama guinea pigs can get pregnant almost immediately after giving birth. Mother should be away from daddy for at least a few weeks before re-mating. It is not healthy for a piggy to stay in a constant state of pregnancy.
All mommies should be allowed at least one month to recover before put back with the male. Also remember that you should not breed them too much. Every time a piggy has a litter, her life span shortens. In addition, babies should be handled right away in order to get them use to humans.
I hope I helped, let me know if you need anything else! Good Luck!