NO SUCH THING
I carry my pocket constitution everywhere I go. When I hear this, I always pull it out and ask them to show it to me.
People should read Roe v Wade. The SCOTUS first had to create a right to privacy (also not in the constitution) and then they found the right to an abortion in that newly created right.
Interesting that 'The right to life' is one of the certain unalienable rights specified in the Declaration of Independence, but it has been trumped by a right never mentioned anywhere.