Regular as clockwork forever and then a 20 day cycle. Any ideas what this means?

[moodycrab]

Always been very regular. 29 days, then this. I'm not pregnant. I'm 45, could this be the start of peri menopause?

Bump

Yes. :)

Yes, or just another 'phase'. That you've been so regular so long is no guarantee that it'll stay that way. I was most disappointed to lose my clockwork 40 day cycle for a 28 day one in my 30s. Having 13 periods a year really annoyed me!