One conjecture could be that fewer young women with children is correlated with higher rates of diagnosis of mental illness. And if I know I had mental illness, I'd be scared shitless to let it known on the record I had a disorder that a CPS worker or family courts could use against me -- without a child those concerns are lessened. I can also attest having a child means you have way less time for your own personal care, which means perhaps these women now have more time for their own care.
I still think social media / smartphones / etc as an explanation fits the trend more simply & cleanly, but I'm much more open to the idea that I could be wrong.
Prior to the Texas private-enforcement-only hack that occurred just before Dobbs (and was huge news before Dobbs eclipsed it), most of them were either funding/access restrictions that didn’t directly target the Constitutional right just made it difficult to exercise in practice (because that had some chance of surviving the courts), while the rest were struck down (or enjoined, and then struck down later) before going into effect and never enforced, serving primarily as strong social messaging rather than enforced law.
2011-2012 was when the major wave of state anti-abortion laws (135 in those two years) and the first notable state executive measure defunding Planned Parent that represented the beginning (well, the visible conversion to a major active push rather than mere rhetoric) of the anti-abortion push by the Republican Party that led to Dobbs occurred.