The Wombplague was a curse unleased upon the Empire of Thassal after their emperor violated the Starfall Truce and used astromancy to strike the eastern kingdoms of Ackenzal. The power of the Anachitis was used to power the curse, and a combination of the Conservators of the fae court and powerful anagogic human sorcerers, including the High King of Ackenzal himself, directed it. The curse prevents those afflicted from being able to create children who can naturally collect energy from the Loom to form a Knot, leaving all infants resulting from Thassali stillborn. This curse has since been circumvented through the use of a Phylactery in the mating process, allowing souls of Thassali to be recycled from one generation to the next.
The Wombplague afflicted those who shared ancestry with the Thassali people, and was not limited to the geographical region of Thassal. It also did not afflict all of those within the region or all of those who claimed to be of Thassali ancestry, as a very small minority did avoid the wombplague, and have since been a complicated political element within the remains of the empire known as the Ruduba.
How those who formulated the wombplague managed to direct the curse in such a manner is shrouded in secrecy, as all records of the method were destroyed at the request of the high king of Ackenzal. This was also the last time the anachitis itself was ever used, as, overcome with grief over his actions, he slaughtered his own family at a celebratory feast, took the anachitis and escaped the city of Wyvar on a nonman vessel.