Sub Fertility is a condition where otherwise healthy couple fail to reproduce despite several attempts.
In India, as per medical experts, approximately 15-20% of people seek advice from the doctors regarding sub fertility issue during their adulthood of 25 to 35 years of age. Considering 400 Million of adult population in the said age group, the number of coulee who face this issue is approximately between 60 million to 80 million.
Doctors suggest two methods to track the fertility trend of women who face such issues. These methods use other Ovulation Prediction Kits (OPK) or Basal Body Temperature measurement. Below table highlights the differences in two methods from a layman perspective.

As one can understand from above table BBT method is more clean, easy and also less expensive. The data generated can be used for further diagnostics if required.