why is there a dip in the bbt at the approximate time of ovulation
Your fertility is highest during the two days before ovulation and the day it occurs, but your basal body temperature changes 12 to 24 hours after ovulation.Since the egg only lives one day, by the time BBT indicates ovulation thereâs little fertile time left to conceive.ecause the spike in body temperature at ovulation is so small, you need a special basal thermometer (available at drugstores for about $10 to $15) to measure it. A basal thermometer records temperatures in one-tenth of a degree increments instead of the two-tenth increments on fever thermometers.