Margaret Carter (Earth-4126)

World War 2
During World War 2, Peggy joined the army and was promoted to Abraham Erskine's assistant. After Steve Rogers was given the super soldier serum, she was placed on the Howling Commandos. It wasn't long until she and Captain America fell in love. Before he was placed in stasis, she discovered that she was pregnant with his child, but never got the chance to tell him.

Raising Alex
Peggy managed to raise Alex until he was ten. As he was growing up, a man named Nick Fury helped raise him. Peggy was attracted to Nick, but he had a reason not to feel the same way. She died of an unknown disease, which might have been related to the one Steve suffered from.