The right to privacy is protected by the Constitution and the court ruled that abortion fell under that amendment.
Roe v. Wade (1973)
"The Supreme Court case that held that the Constitution protected a woman’s right to an abortion prior to the viability of the fetus."
www.law.cornell.edu
"In 1973, the U.S. Supreme Court’s ruling in
Roe v. Wade recognized that the decision whether to continue or end a pregnancy belongs to the individual, not the government.
Roe held that the specific guarantee of “liberty” in the Fourteenth Amendment of the U.S. Constitution, which protects individual privacy, includes the right to abortion prior to fetal viability.
Since Roe, the Supreme Court has repeatedly reaffirmed that the Constitution protects for abortion as an essential liberty, which is tied to other liberty rights to make personal decisions about family, relationships, and bodily autonomy."
The landmark U.S. Supreme Court ruling recognizing the right to abortion.
reproductiverights.org