Oh, by the way, make sure to give the mom calcium-rich veggies while she's pregnant, and I think it's recommended while she's nursing also. Parsely, kale, dandelion greens, spinach, etc. She should also have alfalfa hay - not to replace grass hay, but just as an addition to the diet. Babies can eat alfalfa (in addition to the grass hay) up until about 6 months.
Also, supplement her with Vit. C while she's pregnant and nursing, about 50 mg a day (but not in the water). The 100 mg chewable tablets for humans, cut in half, is an easy way to do this. Piglet doesn't like chewable C tablets straight, like some pigs do, so I crush hers up and roll it up in a piece of wet lettuce - she eats it that way (albeit a bit grudgingly!)
I don't know much about pregnancy/how to tell when delivery will happen, never having had a pregnant pig. You can probably find some good threads on it if you do a search on the Guinealynx forums.