Didn’t the 9 month mark (since delta’s effect on vax rates) pass about 3 months ago in the US (referring to parent)? Or what time/mark event are you looking for?
https://pasteboard.co/uhkdWFvhCf9c.png
edit: this showed up in my inbox during dinner - more evidence https://igorchudov.substack.com/p/new-data-from-germany-birt...
But yes, one way to answer that question definitively would be to do a cohort study on conception rates. Split the data by vaccine status. This can't be done because public health agencies systematically refuse to do this sort of study, nor do they expose the necessary raw data. They don't want anyone being able to answer these sorts of questions. Most data that is available has to be forced out via FOIA requests and the courts.