I've always figured that Vulcans have a sex-related event *every* 7 years. At age 7, Vulcan children are betrothed. At 14, they have their first Pon Farr. So I figured that, yes, Saavik and Spock had sex when he reached that point (and maybe several more times
as he passed through 21, 28, etc) or he would have died again.
And I don't see anything wrong or immoral about that. It was merely logical, a matter of survival, and an act of compassion on Saavik's part. My daughter is approaching 14, and obviously I don't want her having sex until she has finished school and prepared herself for a good life and has found the right partner - but I can promise you that if she was going to DIE if she didn't have sex at 14, I'd be helping her look for someone suitable now
Oh I don't know, he's Star trek
character. They have a way of coming back when you least expect it.
That's it! She and Spock had sex, and she got pregnant - with David!