PeakDay: Faithful Fertility Tracking
Fertility tracking apps have become incredibly popular, but most have secular goals, and many create the risk of exposing your information. Worse, popular mainstream apps may force you to view content directly opposed to your Catholic faith.
Enter PeakDay, created by the Fertility Science Institute of the Couple to Couple League. The Catholic fertility and period-tracking app is designed as a safe, values-driven alternative to apps that often promote birth control, abortion, and other controversial agendas.
For many women, the app serves as an introduction to the broader resources offered by the Fertility Science Institute (FSI), a one-of-a-kind comprehensive online platform that provides scientifically-based resources to millions of Fertility Awareness-Based Method (FABM) users. These include Start-to-Chart programs for young adults, Mother-Daughter courses, and their signature Natural Family Planning classes for couples.
Katie Zulanas, Executive Director of the Couple to Couple League, answered our questions about the app and much more.
1. Why have fertility trackers become popular, and what concerns should women have about mainstream apps?
The popularity of fertility tracking is tied to the trend of overall health tracking and related devices, which is big business. The “FemTech” sector is currently valued at $75 billion. The most popular fertility-tracking app has 62 million monthly users, and the second most popular has 10 million.
Fertility tracking has also increased in popularity because people are less interested in hormonal birth control. Side effects are becoming more well known and women are less willing to settle for “the pill” to solve everything. Additionally, more couples are waiting later in their lives to become pregnant, and they are looking for information and options.
Secular apps are marketing aggressively, and they’re shaping how young women think about their fertility, love, and even their own sexual identity. A large portion of that audience is teen girls. These women are turning to these apps for answers. Instead, they are being targeted, and they have no idea. There are even dangerous secret chats designed to build loyalty.
2. What makes PeakDay different? How does it work in practice? What features are free vs. premium?
PeakDay is focused on helping you become the authority of your own fertility. It makes understanding your cycle simple, beautiful, and faithful. Your information is private and not sold to anyone. We are a 501(c)3 nonprofit and do not sell or share your information with advertisers.
We offer classes to learn all about fertility and charting, but they do not make you dependent on a device or the app. Our books and other resources can help you learn more about nutrition and cycle improvement.
We also provide personal help—from teachers, coaches, and other experts — via the app forum, easy appointments, and a directory of trusted medical professionals and fertility educators. Our Medical Professional portal allows you to review your cycle in real time.
You can use the app for fertility tracking—a feature that is ALWAYS FREE—like a notebook to record and chart your fertility symptoms. This is very appropriate for young women and analogous to paper charting, where you can manually interpret the chart. This is what most of the apps provide—a notebook. It does have the advantage of being able to share charts (via SMS or email) or have a teacher review them.
We are currently offering a 60-day free trial of the premium version, which applies an intelligent algorithm to show the fertile and non-fertile times in your cycle as well as warnings if there are inconsistencies. It also provides statistics/cycle comparisons and can integrate with your Oura Ring, Fitbit, or Apple Watch. Additionally, it includes up to 60 custom fields, which you can use to track almost anything you wish.
3. Who can benefit from using PeakDay? Is it useful for all ages from puberty through menopause?
Yes! We have a “tracking” mode for teens and young women. This allows them to learn what a healthy cycle looks like, and our book “Shorter, Lighter, Pain-free periods” provides strategies to achieve one. This goes along with our Mother/Daughter and Young Adult programs.
PeakDay is also built to go with our popular Sympto-Thermal Method classes (taken by half a million people so far), which can help you understand your chart. Peak Day is great for couples who want to achieve or postpone a pregnancy. Both spouses can log in to the same account and can turn on notifications
We have a great class for postpartum and another one for perimenopause. These are times when your hormones are changing and can be very challenging. It is amazing to have your chart show you what is going on with these transitions, and it is even better to have coaches to answer your questions.
4. Why is it important for Catholic women to understand their bodies and their cycles?
The gift of your fertility is tied to the awesome invitation to become co-creator with God in the creation of an eternal soul—a serious matter! Women need to arm themselves with excellent education to know and understand their fertility cycle, to protect it, and to handle the medical and life situations that come up.
Lately, there has been a growing concern about fertility. Many studies have indicated an up to a 40% decline in male fertility, and many women are experiencing Poly-Cystic Ovarian Syndrome (PCOS) or endometriosis. We don't know exactly why these conditions are occurring, but many speculate that environmental factors and poor nutrition play a role.
There is more reason than ever to learn about fertility so we can guard and protect it. Charting is fundamental to this. It is like learning a whole new language about your body, and it promotes good health. It is also the basis for restorative reproductive medicine, which is cheaper and more effective than in vitro fertilization (IVF). Start with natural first!
5. How will this app benefit Catholic Women in Business in particular?
Catholic Women in Business can appreciate the excellent training and support to promote happier, healthier, holier fertility. Tracking your cycle intentionally focuses you on overall health and wellness. The simple act of tracking your cycle in minutes a day gives you insight into your body, but also encourages you to have healthy habits-and benefits your family as well.
Catholic Women in Business can learn powerful lessons in communication, which is something you practice every day. (If you can talk about mucus, you can talk about anything!) Shared fertility means you share the decision about parenthood each month. It is a good system for married life (other-centered, not self-centered, and not placing all the burden of family planning on the woman). It is not always easy, but it is always good.
6. Tell us a little more about the Fertility Science Institute and the Couple to Couple League.
Fertility Science Institute has excellent resources, including scientific studies as well as additional classes and coaching. Our directory includes screened medical professionals and fertility educators (all methods) who can help you with your fertility questions and treatment. Classes and coaching are consistent with Theology of the Body, but are more of an evangelical outreach, bringing the blessings of Natural Family Planning to the world.
7. Tell us a little more about your background and how you came to be Executive Director.
I received a degree in Liberal Arts from Fairfield University and a degree in Electrical Engineering from UCONN. I started my career in telecommunications and then gained my master’s in Operations from Rensselaer Polytechnic Institute. It was fun and exciting to be a manager of digital network engineering early in my career. I was one of the original telecommuters–and have always loved using technology to solve business problems. From there, I spent some time at home when my children were small–I actually general-contracted our home and then taught general contracting for a few years.
I have taught at a Catholic school, owned a marketing business, and worked for both the Catholic Foundation and the Archdiocese of Denver. All this time, my husband Tom and I were so grateful for the positive impact the Couple to Couple League had on our marriage that we became promoters for the League. I served on the Board of Directors and then became Executive Director five years ago. It has been a true honor.
8. Do you have any advice for Catholics about using apps in general?
Yes! As we have mentioned, many of the secular fertility apps have some alarming dangers that are especially harmful for our children. It is absolutely critical that parents review and monitor any apps they decide to give their children access to. Fortunately, new laws with stronger age limits are being put into place. However, they are not foolproof. Be careful!
Even as an adult, please be critical and careful of who is giving you advice–from ChatGPT to fertility apps. Who is giving you the information? Where is it coming from? What are the privacy protections? What are the commercial implications?
When we were at Lila Rose’s conference and at SEEK, we heard the same stories from young women who were so grateful for PeakDay as a Catholic app–an app that is scientifically based on intelligent algorithms and does not sell their information nor suggest immoral practices. One of the women at SEEK made me laugh when she shared that she needs to close her eyes when entering her information into a secular app each day because the ads are so awful. (It seems like it would be really hard to use the app with your eyes closed!)
We are currently raising funds to add advanced AI capabilities to our app. This investment is significant because the AI will be trained exclusively on high-quality, scientifically sound, and morally sound sources, ensuring that PeakDay users receive reliable, trustworthy information.
9. Can you share any advice about how Catholic Women in Business can develop their own apps?
There has never been a better time to develop an app. Today’s tools make it possible to move quickly from idea to execution, with platforms like Bubble and FlutterFlow allowing you to build and test concepts without coding.
In the current environment, the most effective approach is to clearly define a business problem, develop a rapid prototype, and test whether your solution truly works. Once the problem is validated, you iterate and refine. A working prototype then allows you to assess costs and benefits more accurately and make a compelling case for investment or support.
If you are serious about developing an app, it is also essential to think early about how you will market it–who your audience is and how you will reach them–as this is critical for long-term success.
The vocation of a Catholic woman in business is not merely professional; it is deeply personal and profoundly sacred. As Vocation of the Business Leader, a reflection issued by the Vatican, reminds us, our work is an extension of our call to serve: to build cultures of dignity, to protect the vulnerable, and to draw those around us toward a holier, happier life.
Like a mother who nurtures and shields, the Catholic businesswoman brings that same love into every product she builds, every team she leads, and every woman she serves. PeakDay was born from that calling–and it is your calling, too. The world needs you!