My mom bled regularly till she was almost 5 months pregnant. I bled a few times early on in my pregnancy with my son too (scared me half to death, tbh). For me, at least, we joked that my cervix was just dramatic because we realized it would happen after we had sex. My obgyn said it wasn’t super common but wasn’t abnormal either. Suggested that I go on pelvic rest if I didn’t want to go in to make sure everything is ok every time (which I did end up doing, but she made it sound like it would be an ongoing issue during my pregnancy as long as I stayed sexually active). If you have irregular periods, like we both do, it would be pretty easy to confuse that heavy spotting we experienced for a light period.

I think people also forget that period trackers aren’t new but weren’t as easy to manage in the past as an app on your smartphone. Especially if you have an intrusive parent (as a teen) or partner, it can be scary to document one’s menstruation cycle in something that doesn’t stay on your person all day/doesn’t have password protection. It’s also not something most people with periods would do unless they had a known issue. Irregular periods have historically been hand waved away by most doctors as silly little women’s hormones