ROUTINE healthcare (dental, farrier, worming, etc.) must not be underestimated with broodmares. This includes adequate nutrition, especially in the last third of the pregnancy. A mare being too fat is as bad as being too thin.
There should be a regular de-worming programme in place using faecal egg counts and strategic de-worming, to prevent resistance to wormers. Worm burdens can be serious and even fatal in foals.