A wearable sensor that helps women monitor and record their body temperature to calculate which days they are most likely to conceive. The sensor, named Tempdrop, can be worn with an armband or stuck directly to the skin to measure the basal body temperature (BBT), the lowest temperature a body reaches during sleep. BBT holds important clues for women who are tracking their menstrual cycles and want to see what days they are most likely to conceive. In order to be accurate, basal body temperatures have to be recorded at the same time each morning. Tempdrop records fluctuating body temperatures while its user sleeps, Tech Crunch reported.