Gestation crates that confine pregnant sows for most of their pregnancy have been extensively studied, with scientific consensus that they cause significant welfare harm.
The scientific case against gestation crates is robust and has been accepted by regulatory bodies in multiple jurisdictions. Sows in gestation crates cannot turn around, cannot perform rooting or nesting behavior, and cannot engage in normal social interaction with other sows. The behavioral consequences are clear: crated sows develop stereotypic behaviors including bar-biting, repetitive head movements, and standing behavior that indicates chronic frustration. These are not trivial behaviors but indicators of psychological suffering in an intelligent, highly motivated animal. The welfare case has been accepted by the EU, multiple US states, Australia, and New Zealand, yet gestation crates remain legal and common in many major pork-producing countries.