I am no expert but i would take it to mean that low serum progesterone could result in someone not actually ovulating therefore if they didn't ovulate then there is no point using the cream. If one does indeed ovulate but it is found they have low progesterone prior to "O" (as judged by known preffered levels) then progesterone may help with this luteal phase defect.

So, if you know that you do ovulate (temp taking, 7DPO blood test etc) and you know you have a short luteal phase (less than 12 days between "O" and AF) then the cream may help. I have to confess that I used it for the same reason and found that for me it didn't really make a difference. But, everyone is different.

But you have to establish that you actually do ovulate first or else the cream won't be of any help.

Hope this has been of some help to you and I apoligise if I have been too confusing.

Best wishes
Debbie