In factory farms pigs are born in a shed in a bare metal farrowing crate without bedding, and "finished" rapidly in a group pen until the required economic size for slaughter is reached.
Some sows and boars are kept for breeding. Factory farms confine pregnant sows in "sow stalls", a space little bigger than their own body, for up to the full 103 days of their pregnancy. The sows can only stand, lie down or take a step backwards or forwards. After this confinement the sow will have her piglets in a barren "farrowing crate", and then the cycle will occur again.
The close confinement causes mental pain, indicated by sows chewing the bars of a stall, head waving and pawing the floor.


Photos: from the websites of Animal Freedon and Animals Australia, assumed to be of puboic interest and therefore in the public domain
Animal freedom (2004) The worst abuses in factory farming. http://www.animalfreedom.org/english/information/abuses.html (accessed 4 October 2004)
Animals Australia, the voice for animals (2004) Pigs. http://www.animalsaustralia.org/ (accessed 4 October 2004)