Ovulation predictor kits are available at pharmacies without the need of a medical prescription. These kits detect the rise in levels of luteinising hormone (LH) exactly before ovulation. They are easy to use and usually more accurate than measuring basal body temperature. They can detect ovulation 24 to 36 ώρες before and therefore can increase the chances of conception from the first month of their use. However, they are not infallible. They can measure LH (giving a positive or negative result, but not a specific value measurement), but they cannot detect if ovulation has occurred. The levels of LΗ may surge even without the release of an oocyte from the ovary. Small level increases in LH may be observed before the LH surge that leads to ovulation. For more accurate results follow the following instructions: If you have a 28 day cycle, start the ovulation prediction kit on the 11th day and use it for 6 days (or for as many days as the producing company recommends). If your cycle is long, for example 35 days, start on the 14th day for 9 days. Woman that most frequently buy these kits are those that do not have a steady cycle and therefore are less satisfied by them. If your cycle varies between 28 and 40 days, ovulation can occur between days 14 and 26 of the menstrual cycle. These kits allow for the detection between 5 to 9 days.