Throughout nearly the entirety of their 112-115 day pregnancies, most breeding sows in the United States are confined in gestation crates (also known as sow stalls)—individual metal enclosures so restrictive that the pigs cannot turn around. Crated sows suffer a number of significant welfare problems, including elevated risk of urinary tract infections, weakened bones, overgrown hooves, lameness, behavioral restriction, and stereotypies. Due to concerns for the welfare of intensively confined sows, legislative, industry, and corporate policies are increasingly phasing out the use of gestation crates.
The Humane Society of the United States, "An HSUS Report: Welfare Issues with Gestation Crates for Pregnant Sows" (2013). IIA. 25.