Goal: track ovulation

The time window for getting pregnant is short, lasting just six days per cycle. What’s more, the probability that you’ll fall pregnant isn’t the same on all days. How can you tell the best time to conceive?

If you bet on pregnancies, you wouldn’t stand a very good chance of winning, because studies indicate that the statistical probability of falling pregnant is between 20 to 30 percent per cycle – and only on three of the six fertile days (i.e. the three days that are closest to ovulation). Four days before, the chances of conceiving are only 10 to 12 percent, while five or six days prior to ovulation the probability falls to between 0 and 5 percent. This brings us to the critical question: when do I ovulate?

Here’s how it works: All you have to do is wear the Ava bracelet during the night – the bracelet does all the rest. Ava detects the very first signs that the fertile window is beginning, and confirms when it ends. You also get to know the details of your cycle and find out valuable information on your sleep quality, stress levels, resting pulse rate and much more – before, during and after pregnancy.

How fertility apps work

Fertility apps would appear to be a simple way of calculating your ovulation cycle and fertile days. However, they're based on a standard cycle, according to which ovulation starts 14 days before your next period. The problem is that 70% of women don’t have standard ovulation cycles (source: Ava). As you only have three up to a maximum of six fertile days per cycle, it can be critical if you miscalculate ovulation by just two days.

Another way to determine the moment of ovulation is to study the development of your hormones. Five days before ovulation, your oestrogen levels increase. This can be determined either by observing the cervical mucus – the discharge is stretchier, more transparent and thinner prior to ovulation – or by using a commercially available ovulation test. These tests work along the same lines as pregnancy tests: you either urinate on a test strip directly or dip it in a cup of urine. The results are based on the levels of oestrogen and luteinising hormone (LH) which increases around 24 hours prior to ovulation. The disadvantage of ovulation tests is that if your hormone levels are not high enough, they show the increase too late or not at all. And frequent visits to the toilet with test strips can be annoying. Another way to determine the point of ovulation is to observe the levels of progesterone, which increase after ovulation. This is signalled by a higher body temperature. However, as soon as you register an increase in temperature, ovulation is over. In fact, taking your temperature is another way of determining your fertility window. After ovulation your body temperature rises by round 0.5 degrees. If you observe your body temperature over a longer period, you can determine the days on which you are fertile. At least in theory. This method is very imprecise and highly prone to error.

Source: Studies: Wilcox, Human Reproduction, Colombo, Demographic Research, Ava and Swissmom

*Study: Allen J. Wilcox Clarice R. Weinberg Donna D. Baird. New England Journal of Medicine, December 7, 1995.