Most fertility apps have the same standard features: places to enter the length of your menstrual cycle and the number of days that you bleed and, often, a calendar that will predict your next cycle based on previous cycle history or generic averages. This predictor is helpful because not every day of your cycle is a day that conception is possible or likely. Being able to narrow down your window of fertility is helpful, though studies have called into question how accurately apps can do this.

The fertile window is calculated differently depending on what app you are using, but the basics are the same. The majority of apps will attempt to predict your fertile window to help you achieve pregnancy more quickly. It’s important to keep in mind that it may not be completely accurate; it’s a prediction. It works best when you enter as much data from as many cycles as possible, which allows the app to track fertility based on your history and not a generic average.

The body gives off certain signals when you are ovulating, meaning you are near your fertile window. Fertility apps may allow you to track these signals to help predict this window. Cervical mucus is one thing to track. Ideally, you should track not only the presence of cervical mucus, but the consistency and quality of that mucus. You may also want to track the position of the cervix to help you achieve pregnancy by determining when your cervix is most amenable to conception.

Basal body temperature (BBT) is another form of data used to try to predict fertility. This method involves taking your temperature every morning before any other activity, using a thermometer that can measure to a tenth of a degree. Tracking the changes in this temperature can show that ovulation is about to occur. Manually charting this data is possible but prone to user error. Combining this with other symptom data improves the prediction outcome. Many apps let you track these measurements.

With most apps, every cycle you track will increase the personalization. This basically means that the more information the app gathers, the better it will help you understand your fertility. More data often allows these apps to better predict when your period will start, how long your period will last, or, in the case of fertility-specific apps, when your fertile days are likely to be. Some people also try to use this data in methods of sex pre-selection when trying to conceive.

While trying to pinpoint your fertile window is crucial if you want to conceive, you also need to understand the limitations of the apps that aim to do this. One study looked at a variety of fertility web sites and apps and found that the range of the fertility windows they predicted varied widely and were found to be inaccurate. While this study didn’t say how that altered pregnancy rates, it’s important to understand this limitation when using these apps to try to conceive.

Interestingly, there is a lot of research being done on the use of apps to avoid pregnancy. There are even studies looking at how to evaluate apps for their use in preventing pregnancy. The DOT Study Protocol is a clinical trial that is looking to determine whether people are using these apps correctly. The study’s results will likely help in the evaluation of fertility apps designed to help people conceive as well.

More research is being done on the use and effectiveness of fertility apps. One large study looked at more than 7,000 women tracking their cycles. While the study authors felt they had improved upon previous studies, they believed that these apps were only good for women in the beginning stages of trying to conceive. This means that you should talk to your doctor or midwife to get the best advice on getting pregnant If you are having trouble.

Fertility apps may not have the history that paper BBT charting does, but it puts the power and information you have at your fingertips. With an app, that information is readily available and in an easy-to-understand format. There’s a specific app that will appeal to everyone. Using an app may also help you identify when you need to be seen for medical fertility support, or help diagnose health issues earlier.

It is important to understand that these apps are simply tools to help you understand the data that you have at your disposal. They are not meant to replace the advice of your doctor or midwife and may or may not be as helpful as you hope. If you are experiencing difficulty in getting pregnant, be sure to talk to your doctor about what apps are best for your situation.