South Korea introduced the ban in 1987 to try to prevent abortions of female fetuses in a country that had traditionally favored sons in the widespread Confucian belief that males carry on family lines. Abortion has also been illegal but practiced widely.

On Thursday, the Constitutional Court said it was too restrictive to ban doctors from telling parents the gender of the unborn for the entire pregnancy because there was little chance of aborting fetuses older than six months due to risks for mothers.