We have a gilt that is now at day 118. She was AI'd, so we know her true expected due date. We watched her very close and never saw a heat after. However, she looks like a pig a week away from delivery. She is big bellied, swelling in the vulva comes and goes, a slight clear discharge. She acts like she is nesting. The teats are slowly forming, as if they are trying to get milk, but then nothing. She has been this way since day 114. I have been told, once she gets milk, she will deliver in approx. 12 hours. However, I have also been told, its is not abnormal for a gilt not to get milk until she delivers. I am to a point, I do not have a clue what to do.

Since you are sure of her due date, I would induce ASAP.