Any time a medical issue is discussed I would encourage always giving the details of the patient because what is normal for a 10 year old mare that has had many foals, may not be for a 3 year old mare having her first foal.
Post partum contractions are not only normal, they are good and needed to expel the placenta and fluid to help prevent uterine infections. Mares can be bred back in 9 days (and sometimes sooner), so there are dramatic changes that need to take place.
Many times mares are uncomfortable because their instinct to foal away from all disturbances is frequently messed up by our modern husbandry of housing animals together and human contact. I encourage people to get away and let mother nature take its course only intervening when absolutely needed.
Dr Taylor