There’s a direct quote in ROTJ on Dagobah when Obi-Wan is telling Luke about his sister
“To protect you both from the Emperor, you were hidden from your father when you were born. The Emperor knew as I did that if Anakin were to have any offspring, they would be a threat to him”
This would mean that Vader/Anakin didn’t know that he had a son in ANH or that his wife was pregnant when he turned to the dark side. This would make sense since the closest he came to know who Luke was in ANH is in the DS trench run when he says “The force is strong with this one”.
The best way to fix this in the PT is to overdub the dialogue between Anakin and Padme when she reveals she’s pregnant to him and have the visions of her dying in childbirth removed and make his turn to the dark side a seduction of power. Then on Polis Massa, when the GH-7 medical analysis unit is speaking to Obi-Wan is when it reveals she’s carrying twins, with both of them being nameless and genderless when they’re born.