I'm all for normal birth---water, baby, placenta. It's this gnostic teaching I'm against.
And by little and little that light withdrew itself until the young child appeared: and it went and took the breast of its mother Mary.
-PoJ-
This young child who's able to take the breast, this abnormal birth left Mary intact. It's the later east gate metaphor (birth from out her side as the new Eve.) Christ didn't open the womb. It remained shut.
In turn this false teaching is found here.
"But certain disciples [Marcion's Apelles?] compelled to be wiser than their teacher, concede to Christ real flesh, without effect, however, on their denial of His nativity. He might have had, they say, a flesh which was not at all born. ..."
ANF03. Latin Christianity: Its Founder, Tertullian - Christian Classics Ethereal Library
IOW, the most likely author of PoJ is Apelles who supposedly agrees Christ had flesh, but denied the normal birth. That's the PoJ as shown.
From the recently closed thread, there are people who agree with the abnormal birth, but I'd guess they don't really know its gnostic source, rather than the scriptural normal birth.