What is the 'undue burden' standard in US Supreme Court doctrine?

The 'undue burden' standard is a legal test established by the U.S. Supreme Court in the 1992 case Planned Parenthood v. Casey. It holds that states cannot place substantial obstacles in the path of a woman seeking an abortion before fetal viability, unless the law serves a legitimate state interest. This standard allows for some regulation of abortion, but emphasizes that any restrictions must not create significant barriers for women. The standard aims to balance a woman's right to choose with the state's interests in regulating abortions.