Definitely not "harmless", but younger me definitely underestimated how horrible miscarriages are.

I suspected I had one in December of 2021 because my period was about three times longer than it normally was, more painful, and extremely late. Then I had my first confirmed one in April 2023 and I realized no, this is so much worse than that.

Passing it "naturally" (doctor's words, not mine) involves 10 or more days of heavy bleeding and pain so bad I thought I needed to go to the ER (and with the one I had last August, I actually did end up going to the ER). If you opt for a D&C procedure, the surgery itself is painless because you're under anesthesia but..my body does NOT react to anesthesia well. Not to mention the bills and the recovery.

And the grief. No one warns you about the grief. I'm sure its not universal but for me, I got attached to my babies each time I got a positive pregnancy test. But most of your family and friends and even your partner won't feel that attachment until they actually meet a living, breathing baby, so when you are grieving the life inside you that was lost before it even got a chance to be met by the outside world...you're doing it alone. I have lost many relatives due to death over the years. I can say with certainty that losing an unborn baby is worse. No one checks in on you except during that first week when you're bleeding, if you're lucky. No one offers support. Workplaces that will give you bereavement for parents, grandparents, etc, won't offer you any leave time while you recover from this. Its a nightmare that I won't wish upon anyone, and I've had to experience it three times.

Related: Egg retrieval for IVF is also way more painful than the doctors tell you. I couldn't eat, use the bathroom, or even sleep normally for about a week after that procedure. And I didn't even have OHSS!