A week passed by after the incident with the King of Bernel Kingdom and the creation of the product that came from the Laporal Fruit which Elaina named as the Fertility Potion.
Although the testing phase was over, it was only to determine the right amount of potion intake to make the potion be effective. The effects itself has yet to be finalized and fully determined as it is not an immediate effect that can be seen or experienced immediately. Sure, the detection magic used by magic to determine the health of someone is working but Dr. Fey wanted factual and visual confirmation that the potion works as it is intended.
Dr. Fey already told Yona which she passed to Elaina that the medicine did restore the fertility of women but since they needed further observation, Dr. Fey delayed the final observations that will determine the success of the medicine and that is if the women who have success with restoring their fertility would be able to conceive at long last.