Actually unborn children are considered persons for legal reasons in many cases. So it's not a myth. They myth is that designating some arbitrary point of personhood is anything but self-serving.
Care to comment on the obscene nature of the act that provides content for what you perceive as obscene pictures? Or are you going to take a pass on that comment for some reason?
This is a common misperception.
In almost all those cases those unborn children are not considered legal persons per se. The cases that seem to allow this concept are generally property cases. The law allows that these unborn children do have claims on property if they are born. In the case the case where the unborn dies before birth, the title of the property is not shown to have ever been in possesion of the unborn.
For example, death taxes. A person dies leaving property to an unborn. The property of the person who died is subjected to a death tax. If the unborn dies before birth, there is not another death tax levied. The property goes to the next person who has claims.
The myth is that designating some arbitrary point of personhood such as conception is nothing but self-serving.