A recent study presented at the 2016 annual meeting of the American College of Obstetricians and Gynecologists found that many fertility calculators found on popular websites and smart phone apps do not accurately predict a woman’s precise “fertile window”. Of the 53 fertility calculators tested, only 4 accurately predicted the best days for conception. The researchers put the same information, including an average menstrual cycle length of 28 days and the same date for the last menstrual period into each fertility calculator. The results for the “fertile window” varied widely and some incorrectly predicted the day of ovulation.
This new study highlights the importance of not relying solely on fertility calculators to predict ovulation. This study used an average cycle length of 28 days, but a normal cycle length can vary from 21 to 35 days. In some cases, women may benefit more from using an ovulation prediction kit.
For women who are struggling to conceive, we recommend speaking with your physician regarding your individual cycle length and its variations.