My ferning pattern results don’t align with my BBT thermometer results. What does this mean?

BBT thermometers provide a shorter spike, typically lasting 24-36 hours. However, ferning may last closer to 72-96 hours, providing an extended window in which to remain sexually active and maximize the chance of conception. Also, there are more factors that may affect your body’s temperature than factors that may affect your saliva chemistry, so the two methods may not coincide perfectly.