Is a defendant's argument that he is not guilty of the crime of second degree murder of a fetus challenge his guilt of second-degree murder?

We have no difficulty deciding that the argument defendant here asserts challenges his guilt of the crime of second degree murder of a fetus. Properly stated, defendant's argument is that he is not guilty of the crime to which he pleaded no contest, he is guilty of some lesser, unlegislated, crime. "`A guilty plea amounts to an admission of every element of the crime and is the equivalent of a conviction.' [Citation.]" (People v. Jones (1995) 10 Cal.4th 1102, 1109, 43 Cal.Rptr.2d 464, 898 P.2d 910.) By his plea, defendant admitted he was guilty of second degree murder of a fetus. His "due process" claim goes to the question of guilt or innocence and is not cognizable on appeal.