Those weren't his words, and his actual words (which he quoted above, acknowledging their ambiguity) could be (mis)read as meaning that injecting the urine killed the rabbit a few days later, especially since he also wrote "apparently [frogs] could survive the urine injection".
> FWIW the rabbit always died whether you were pregnant or not :(.
It's not that an injection of urine if a pregnant woman kills the rabbit.
It's like the rabies test on the brain. We cannot look at the brain before you're dead, because the act of looking at it would kill you.