-1 for changing “Death” to “Birth”.

If we change it to “Leia foresaw the birth of her son”, we’re implying that parenthood is sufficient reason to quit being a Jedi - as if you can’t both become a (force using) major player on the galactic stage and also raise a child. This also doesn’t quite work because she remains a politician and general, both major player roles, whilst still having young Ben.

As it stands, as “Leia foresaw the death of her son”, that’s saying that Leia (implicitly) saw her son’s birth and existence, but then (explicitly) saw that continuing down the Jedi path would end in tragedy, so she sought to focus on her political and military strengths instead of leaning into the force as a solution.

We have to remember that one of the main themes of the Star Wars franchise is that fear of loss leads to the darkside.

Anakin feared the loss of Padmé, and this gave him an emotional vulnerability which Palpatine was able to exploit. (Hell, Anakin even foresaw the death of Padmé, leading him to become Darth Vader.)
Luke feared the loss of his friends, abandoning his training under Yoda and going to face Vader on Bespin too early.
Luke later feared the loss of his sister, which on the second Death Star was almost successfully exploited by Palpatine in the scene where Luke almost gives in to the dark and batters Vader against the throne room railing.
Leia feared the loss of her son, which in the current context we could view as a similar potential vulnerability if she continued down the Jedi path.

She’s also proven quite right - Luke loved and trained his nephew Ben, overreacting (or at least acting too rashly in the moment) in response to his fear of losing Ben to the darkside. He recognised his failure in that moment as a reaction to the fear of loss yet again, leading him to question that core belief, and ultimately to shut himself off from the force and go into exile.

Luke even teaches Rey as one of the core lessons, “confronting fear is the destiny of the Jedi”. What fear is he referring to there? I think it’s safe to say, fear of the loss of a loved one. Luke learned this lesson - too late for himself, but in time to pass it on to Rey as the inheritor of the next generation of Jedi. Leia recognised the threat of her feelings for Ben should she become a Jedi, and sought to avoid the issue by not continuing down the Jedi path.

The Jedi of the Republic knew of this vulnerability and forbade emotional attachments - romantic love and parental love. Ultimately, the Sith under Palpatine were able to exploit this forbiddance too. I believe that the later journey of Luke and Leia (from about ROTJ onwards through the Sequels) is about them recognising that denying love is just as dangerous as permitting it, and that instead, healthy emotional processing of emotional attachments (and learning to let go) is part of the solution.

It’s a tragic irony that Luke’s fear of Ben turning to the darkside helped turn him to the darkside, and also that Leia’s fear of Ben’s death ultimately put him on a path which still led him towards his death - but it’s a triumph of Leia’s love and willpower that she was able to help return Ben to the light before he died.