While they invented it,ts well mentioned that even so,missuses of those potion werent uncommon,and when these happened most kids were given to adoption,they did provide services that involved get child for couples who werent capable to have kids of their own,and i suspect Sister Theresa developed the potion just so they could help couples without having to get a packed womb
As far as I recall the service was offered either by volunteers useing the Potions and administration in the temple or Alcolytes.
Priestess were on a strict Potion of Bareness diet and the high Priestess was meant to monitor that everyone was takeing their Potions.
The High Priestess suspects that some of the lower priestesses (that gave special services to VIP donors) neglettet their duty of takeing the Potion when they were found Pregnant, but once even the upper echolon got Pregnant she noticed the Problem, and considering that Theresia was the only women not Pregnant concluded her involvement in the matter.
Zivah told us that women that became single mothers did join the temple as Alcolytes and after giving birth becomeing Priestesses... those Children were given up for adoption.
That's all correct, but doesn't mean much. If i remember the story correctly, the temple already served the goddess before it was destroyed in the goblin wars. And she will not have been prudish in the past either. I suspect the barreness came later and was used to protect the followers.
Yes that temple used to be a temple of Qetesh from the start, but no the Potion of bareness were known to the order since the start.
The administration to the Alcolytes and Priestesses was mandatory since their religion was based on giving pleasure.
A Pregnant woman can't fulfill her duties to the goddess so they were made barren with the Potions