Piglet mortality before weaning is an important cause of economic loss in the pig production. Most piglet mortality occurs during the first four days after birth, and the major part is caused by non-infectious conditions. The causes can be found in the sow, the piglets as well as in the environment. This article gives a review of the most important causes related to the sow or the environment. Regarding sow factors, emphasis is placed on lactation problems, aggression, parity of the sow and litter size. Concerning the environment, the effect of temperature, trauma and poor herd health management are discussed
