LB – it seems that there was a woman whose doctor told her that she can only conceive during a time period when, according to halacha, a woman is forbidden to her husband. Rav Kook said that this can’t be correct according to Chazal, and Chazal are more reliable than doctors, and therefore he was not willing to permit her to her husband during the particular time period in question.
He also then went on to say that the doctors wanted to do away with metziza because they thought it was dangerous, but Chazal say differently and the doctors have no validity against Chazal because Chazal’s chachma comes from the Torah.