Probably , but you never know. It's not just about the udders though. When the foal starts to move into position, your mare will look narrower from behind. Looseness around the base of the tail, her lady parts getting swollen and relaxed, looking hollow in front of her hips, passing the mucous plug, changes in attitude, and a few other things. You kind of have to look at it all to get a good idea when it's time.