I agree, its difficult to reconcile this law (I guess its still a bill now, actually) with the first amendment.
While its probably possible to construct a law like this that would pass muster, doesn't sound like this one does.
On "two weeks before conception", that's actually very simple. In many cases its simply impossible to know when conception actually has taken place. The widely used medical standard to mark the beginning of pregnancy for medical recordkeeping is simply from "the last menstrual period", since that's an externally visible sign and most women do know exactly when that was. LMP, also happens to be two weeks before conception in most (but not all) cases.
The issue here isn't really switching to the most commonly accepted medical standard for marking the start of pregnancy, but rather explicitly changing the time frame in which abortions are legally permissible.
IE, the problem isn't specifically that AZ is using the LMP to start the clock, is that the law in question bans abortions more than 20 weeks afterwards, going against Federal precedent requiring legal abortions before fetuses could survive on their own.
