Why are ovulation test strips always weak? Ovulation test strips are a common tool that helps women detect whether they are ovulating. However, when some women use ovulation test paper, they will find that it always shows a weak positive state, that is, the color of the test paper is not much different from the color of the control line. What is the reason for this? First of all, it may be a problem with the ovulation period itself. Generally speaking, the ovulation period is relatively short, and most women do not ovulate smoothly every month. Therefore, even if you use ovulation test strips, sometimes there may be a weak positive or no obvious positive at all.