This is true, but I've also read studies that within 24 hours of quitting smoking, there are already noticable health benefits and lowered risks of problems, which continue to get better the longer the time has elapsed. I'm not arguing that smoking between the ages of 15-18 & 20-27, as I have done, will have no effect, but if I quit while I'm still young -- I probably have a few years left where one way or the other won't matter too much -- then by the time I reach an age where heart disease, lung disease, cancer, stroke, etc. are more likely dangers for me, my lungs will have had a decade or so to recover and hopefully that will be enough. I've gotten a few grey hairs already, and a few wrinkles, so I know that the time to quit will be soon, but I don't know if I'm ready to do it just yet. The last time I quit (for an entire year, cold turkey), it was because I got tired of the way I smelled and didn't want to smell like that anymore. I only started up again because I had friends who smoked (who have since moved away). I think if I can get into that headspace again, where I really don't want to smoke and am tired of it, then I will be able to quit easily, whereas if I'm just doing it because of knowledge of health risks in the distant future -- that's not immediate enough to make it easy.
As far as pregnancy goes, I think that as long as I quit at least a year before I'm planning to get pregnant, the fetus will be okay. My grandmother was encouraged by her doctor to smoke during pregnancy to calm her nerves. (This was in the early 1960,s I believe, and I'm fairly certain the effects of smoking were known to doctors at that time, but i dont know) The kid was born weak and sickly with all sorts of allergies that none of his siblings shared. He survived, and it could have been much worse than allergies, but it was still a bad thing.
Just because quitting smoking will allow your body to heal some of the damage, doesn't mean it will allow your body to heal all of it, even in 10 or 20 years.
An exercise:
Name something that you do not do but should/wish you did/are told you ought, or that you do less than is normally recommended. (For instance, "exercise" or "eat vegetables".)
Make an exhaustive list of your sufficient conditions for avoiding this thing. (If you suspect that your list may be non-exhaustive, mention that in your comment.)
Precommit that: If someone comes up with a way to do the thing which doesn't have any of your listed problems, you will at least try it. It counts if you come up with this response yourself upon making your list.
(Based on: Is That Your True Rejection?)
Edit to add: Kindly stick to the spirit of the exercise; if you have no advice in line with the exercise, this is not the place to offer it. Do not drift into confrontational or abusive demands that people adjust their restrictions to suit your cached suggestion, and do not offer unsolicited other-optimizing.
To alleviate crowding, Armok_GoB has created a second thread for this challenge.