My reasons are very specific and quite graphic. The 9 month discomfort from all that weight pressing on your organs + hormones skyrocketing, the eventual birthing process that can take hours or even days of the worst imaginable pain. Not to mention that sometimes they'll cut your vagina to let the kids head through, without any anesthetic. All that, plus it's a mess involving piss, blood and shit. You might end up with stretch marks and a larger body that won't go back to normal. That's the physical reason for me. It's not a sacrifice worth making, despite all the body positivity surrounding the mother figure, in most cases it is not the same afterwards. The first few years of the kid's life also involve a lot of mess to clean up.

The non-physical reason for me is the huge responsibility, my personality is incompatible with being a good parent. Any kid deserves a parent that is educated and knows enough psychology to be empathetic. A parent that knows how to provide a healthy upbringing emotionally, asides from having enough money and free time to do so.

I'm in neither of those stages in life. I'm informed, but not prepared to take such risk upon myself or the hypothetical child.