I haven't heard of chayote being a concern the way unripe papaya is, but because you're pregnant it's really worth checking with your gynae or PD just to be safe, especially since you're already thinking about the latex angle. I know it can feel like there are so many things to watch out for when you're expecting, so it's better to get a clear answer from someone who knows your pregnancy history rather than guessing, hor.
if u have doubt then better to ask your gynae or just don't eat it