A couple of signs of a piggie being pregnant are:
1. she'll frequently drink more water than usual
2. she'll eat more than usual
3. slight change in behavior (dosen't like to be touched alot especially around the belly area)
4. as the pregnancy proceeds, you'll notice she'll take on a pear-like shape.

when she starts to look like a pear, you'll want to handler as little as possible, but still be there to interact and supervise her. you'll also want to increase her vitamin C and her hay, as the babies will recieve all the nutrients they need from their mommie. you can also give her alfalfa hay too (for the babies),so they'll get the calcium they need as they grow and when they start to nurse (even though they'll start to eat alittle solid food and hay on the third day). hope this helps you somewhat.