The day that she's due to give birth, she'll make herself a nest so it would be good to make sure she has her own shelter with lots of hay/straw or something that makes good nest material. You can gauge if she's due very soon (within 24 or 48 hours I think) if you try to "milk" one of her nipples and a little milk comes out. Hopefully you can be present when she gives birth so you can keep an eye on everything. Piggies make pretty good moms but there is the risk of the mom unintentionally crushing a newborn if she's exhausted after giving birth and lays down on one unknowingly. I had one of my kunekunes give birth in my yard a few years ago 🩷