If you believe all people are created equal, then rights have to start at the time of creation.
Perhaps you should take the time to consider the practicalities of this approach, such as:
If the state acknowledges that an entity has rights, it has be able to acknowledge the existence of that entity. So... all conceptions must be registered?
Any women carrying unregistered foetuses are committing a crime?
Any miscarriages at any stage must be investigated as criminal negligence at the very least?
Should these feats of stupidity be accomplished with less tax revenue, or is this something you'd support a tax increase for?
Personally IMO if you've got such a hard-on for this idea, then a legally required permit system for conception would make a lot more sense.