If you want to become pregnant or avoid it — there's an app, called Dotâ„¢ (Dynamic Optimal Timingâ„¢), that could help you track your reproductive cycle. The app is currently being tested on 1,200 women in real time.

The app is fairly simple. It’s based only on the first day of a woman’s menstrual cycle. Researchers from Georgetown University Medical Center’s Institute for Reproductive Health (IRH) analyzed World Health Organization data from 1,000 women in six culturally diverse locations around the globe. From a careful analysis of the numbers, the team found that they could predict a woman’s fertile days extremely accurately just from a single type of input — the start date of menstruation each month.

The data show that when used correctly, the app would be 96 to 98% effective, which is extremely high. And it gains accuracy for its user over time.

“Our goal is to test the efficacy of Dot as a method to avoid unplanned pregnancy in a real-time situation,” says Rebecca Simmons, a senior research officer at IRH. “We are all smartphone-based, and this study will be conducted on the phone and the app — which is novel but quite appropriate.”

The program allows for a cycle of anywhere from 20 to 40 days, and it alerts the user each day about how likely she is to become pregnant. Which could help a woman either avoid pregnancy or achieve it, depending on her desires.

For women who may not be so familiar with the timing of ovulation and the odds of fertility over the course of a month, the app puts this information literally in the palm of your hand.

“Our work has shown that simple fertility awareness messages are extremely attractive to a wide range of women and can address their family planning needs,” says author Victoria Jennings. “A method that only requires a user to enter her period start date is likely to appeal to many women.”

Other fertility apps exist — there are about a hundred of them, the authors say — but they tend to use other measures along with one’s menstruation date, like basal body temperature. But these variables may be more relevant if a woman has irregular menstrual cycles, and not so necessary for women who have regular ones. In these latter cases, the day of menstruation may be enough, which makes Dot‘s algorithm one of the simplest. And the data show that when used correctly, the app would be 96-98% effective, which is extremely high. And it gains accuracy for its user over time.

So, for those trying to get pregnant, tracking your basal body temperature and writing it on a calendar seems to be very 20th century. If you’re trying to get pregnant, think about giving the app a try. It may be worth trying a few different fertility apps to see if they are in general agreement with one another.

For all the ways in which technology gets a bad rap, this one may be one that could really help us out, whatever our family planning needs may be.

The study is published in the European Journal of Family Planning and Reproductive Health Care.