Silvia Azaña, embryologist at inviTRA, explains in this video whether ovulation tests are reliable for identifying fertile days:
The ovulation tests are a much more precise way to estimate the ovulation moment than the fertile days calculators are. That is why it is used especially by the women who are currently actively trying to conceive at this time, especially when it is delayed in its arrival.
The ovulation test measures the level of LH hormone in urine and can be purchased at a pharmacy. The luteinizing hormone starts to rise exponentially in the period spanning between 24 and 36 hours leading up to ovulation, at which point it reaches its maximum and then starts to decrease.
Therefore, when the ovulation test is positive, the woman is in her most fertile days. Furthermore, the advantage over the calendar method is that it also predicts when ovulation will occur even if the woman has irregular menstrual cycles.
