In conclusion, allowing the sow to move freely before farrowing, reducing the constipation state and avoid excessive fattening during late pregnancy all appear to be key factors in shortening farrowing time and reducing perinatal mortality.
C. Oliviero, M. Heinonen, A. Valros and O. Peltoniemi. Environmental and sow-related factors affecting the duration of farrowing. Animal Reproduction Science. 2010. Vol. 119 (1-2): 85-91.