I am honestly not certain what the cause is but I am simply not getting the birth option at all. I have played previous versions but in 3.20 I am still in the early game (haven't even gone into the cave for the mayor of cedar town yet) and when I get to 100 on the pregnancy progression I do get the dialog for contractions and the prompt that the birth option should have appeared in the skills menu but when I look the option is not present. I have tried a whole new save, reaching 100 in a battle vs from a plant, changing screens, and using the healing skill to drop to 90 then reaching 100 again but the option never appears. I did read through the thread and thought maybe it was the soft lock from skipping the intro that someone else reported but I started a new game, did the intro, and the issue is still present. Notably, when using the healing skill to drop back down to 90 Leah shows two status symbols for her pregnancy state simultaneously and reaching 100 again does not prompt any dialogue reaction.
The game is very glitched at the moment, as there is numerous things that need to be fixed. The amount of it has pushed back the date of the next patch, along with other things going on with the content creator that is not my place to say. But, the patch is coming soon; I know that with absolute certainty.
It would be a mac in my case but unlikely, as when I emulated the previous version on it the hot-spring trick worked for Leah too. Might try a fresh download to see if it's just on my end, but I'm not getting actual errors so the game is probably just not properly setting the correct flag when changing costumes.
Wait. You're talking about the spring in the fairy forest right? Of that's the case, then people have reported that one. My issue was that there are specific dialog from the last update that never showed up in this update, as I thought it was glitch. The previous dialog from the last game made it immersive in my personal opinion, or the choice of having different dialog coming from different characters; instead of ignoring the obvious. I found that very interesting, which is why I like the series.