At what age is it normal for a woman to develop mild degenerative changes in the l5-s1 part of the spine?

>25: You mean on the xray? If so we usually see it after age 25, the findings on imaging don't correlate with the symptoms too much but it's a normal finding to see it past that age group.

By age 60 100%!: I had the opportunity to respond to a similar question you posted in which you indicate you have premature lumbar degeneration. a disc bulge and facet arthropathy. This is not common but occurs rarely as a family trait. As a sports medicine doc I see it in gymnasts, cheerleaders, dancers, explosive collision sport athletes and in obese, tall individuals who sit, drive, stand and load the low back.