T. gondii is a known teratogen (toxic environmental shit that affects embroyonic development), so pregnant women should already be staying away from cat litter.
Schizophrenia, though? Eh.
Maybe. I can see a circumstance where it might cause it. Any time you're doing stuff with your brain, it can go wrong. There's a theory with some traction that cold and flu during pregnancy can cause schizophrenia. And pretty much any time you have something affect the brain, it runs the risk of causing a mental illness. Brain infections, strokes, drugs (marijuana and meth = schizophrenia, cocaine = bipolar disorder, etc)... so it's very possible you can develop mental illnesses from it.
But specifically schizophrenia? There needs to be more research before we draw any kind of conclusion about it. There's a difference between an infection in the spine causing paralysis and that infection by definition causing paralysis. By that logic, bullets cause paralysis. The point being? If it hits you in the spine? Yeah, it causes paralysis, but it won't cause paralysis every time it hits you because that's not the nature of a bullet.
The bigger thing I think we should remember from these studies is that correlational research can never draw conclusions about cause and effect. You should especially never trust a correlational study when it's reported by the news, because it's very probably wrong. If I gave enough fucks about it, I would do a study showing the correlation between reports on "links" found through correlational research as reported by the media and the times they've turned out to actually have any kind of truth. It would be a very weak correlation.
The very act of examining the statistics of two things, be it cat ownership and schizophrenia or left-handedness and violent crimes, creates a correlation. A correlation is the relationship between those two things, whether it's strong or weak or otherwise.
Even if it's an extremely strong correlation, it means next to nothing. Ice cream and murder rates have a strong correlation. Why? Because ice cream sales go up when it's hot, as do murder rates.
So 10/10 would not remove cats from the house over this. They aren't even conclusive correlations anyways. They're early-stage. One of them even says in the abstract "We urge our colleagues to try and replicate these findings to clarify whether childhood cat ownership is truly a risk factor for later schizophrenia."