Knowing when the time is right to try for a baby could soon be as easy as checking the hour of the day. A technology firm has created a wristwatch which can tell when women are about to ovulate and are most likely to get pregnant. The PSC Fertility Monitor works by measuring the changes in the acidity of sweat. This is determined by hormone levels, which indicate how fertile the woman is. The results are displayed on the watchface. 'Trials show the device correctly predicts ovulation to within two days,' New Scientist magazine reported.