At the end of Revenge of the Sith, when Anakin faces Obi-Wan for the big lightsaber battle
Anakin Force-chokes Padme and she is lying on the ground unconscious, but she's still pregnant and Anakin has seen her like this. Then he and Obi-Wan face off and Obi-Wan leaves Anakin (now Vader) for dead.
After this duel
Sidious rescues Vader and tells Vader that in his anger he killed Padme. This would have been right after he saw her and she was still pregnant. Both Sidious and Vader (and most of the galaxy) believe she never gave birth.
But then, at the start of Episode V, Vader is searching for "Young Skywalker," and has figured out that
Luke is his son
So if Vader has figured that out, then he must have also figured out that
he (Vader) didn't kill Padme and that she lived at least long enough to give birth to one child. So Sidious was lying to him when he said that Vader killed Padme in his passion and rage.
While deception is the way of the Sith, is there any indication that when Vader found out
he had been deceived about Padme's death, and that he might have been able to save her during childbirth
Why doesn't there seem to be any fallout or consequences of Sidious' lie to Vader on such an important subject?
EDIT: Since writing this, earlier this evening, I watched the new blu-ray version of Episode V. I don't know when it was retconned in, but in the scene where Vader speaks with the Emperor via hologram, the Emperor says
Luke is "the son of Anakin Skywalker," and adds the usual, "Search your feelings, you know it to be true," when Vader asks, "How can this be true?"
So the Emperor does tell Vader, but considering Vader's obsession with "Young Skywalker" before that, I think it's likely that Vader already knew that. (But it does raise the question of why Sidious would so easily make a statement that would give his lie away.)