Traditionally they're wormed just before farrowing and feed reined back for a couple of days to prevent constipation. Is she already in her farrowing quarters? We put them in a month beforehand and put the infra red lamp on at night from 16 weeks + 3 days, so they're familiar with it when farrowing begins and we can easily see what's happening from outside when we check before bedtime (ours, not hers).