If I had found out I was pregnant within the first year or so of my marriage, I probably would have cried unhappy tears and grimly braced myself for the end of life as I knew it. I was fresh out of college, ready to change the world, and not prepared to have kids.

During that year, my husband and I were using natural family planning (NFP), a method of tracking a woman’s fertility signs and abstaining from sex during fertile phases to avoid pregnancy. NFP is commonly considered a traditional Catholic practice, although today a growing number of evangelicals, leadership and lay, are leaning towards it as they rethink contraception. I had suggested we do NFP simply because none of the other contraceptive methods felt right to me. In the process of taking a class and doing NFP, however, the practice took on deeper significance as a type of spiritual discipline.

I think of a spiritual discipline as an intentional way of creating space for God. Different people may find that different spiritual disciplines work for them, and different seasons of life may call for different spiritual disciplines. In that newlywed season when I was wrestling with what it meant to join my life and calling to that of another person, practicing NFP became a way for me to give God the permission to rattle up my life.

I knew what I wanted – to go to graduate school, travel the world, and eventually write books. Having a baby didn’t seem to further any of those goals. It would have been easy enough to reach out my hand and close the door on that seeming intrusion by using some other, surer form of contraception, but I felt it would be good for my soul to leave the door open – just a crack.

It’s not that NFP isn’t as effective as other forms of birth control. According to our NFP textbook, it is over 99 percent effective if done correctly. But I wasn’t completely sure of my own reading of fertility signs, or of our ability to always abstain during the fertile stretch. And in an age where medicine offers us a myriad of pills, patches, shots, and instruments to keep us from becoming pregnant, NFP isn’t always brought up as an option or trusted by young couples. After all, it is not the convenient, quick fix we so often look for. Instead, we must think about it and do a bit of work. In Christian lingo, NFP is “intentional.”

Just a few years (and one baby) later, we are no longer using NFP, but our experience with this method continues to shape how I approach sex and reproduction. NFP brought an increased awareness that having sex could lead to children. It forced me to wrestle with this reality more on a regular basis, rather than opt out of that consequence more easily. NFP also taught me to relinquish control (or better said, recognize I didn’t have it to begin with) through honoring the mystery of the human body. Based on the Theology of the Body teachings by Pope John Paul II, NFP advocates a profound respect for the human body as the outward manifestation of the human person. I think in some cases Theology of the Body can be taken too far, equating biological function with role and identity. But I agree with the core premise that there is something sacred about our bodies’ design and function, not to be meddled with lightly.

As my husband and I learned about the intricate workings of our own reproductive systems through our NFP class, it became clearer just how beyond our reckoning the whole baby-making business really is. Even if we timed intercourse just right within 24 hours of ovulation, there is just a little over 30 percent chance that one of the millions of sperm will join the egg and create a new human life. Yet every day tens of thousands of children are conceived to parents who don’t plan for them. And tens of thousands of couples yearn for children that haven’t come.

This is not to say we should just throw up our hands at any kind of family planning. As this summer’s Hobby Lobby decision and the subsequent conversations on women’s rights and women’s health made clear, women’s decision to use or not use birth control is a deeply personal one dependent on many factors. But when we do family plan, we should recognize that our bodies are not machines that we can manipulate at will. We can try to avoid or achieve pregnancy, but in the end, it is God who sustains our bodies and who gives new life. This truth can be easily obscured with all the medical advances that promise to give us mastery over our reproductive powers, whether by sealing off or letting loose.

One day shortly before our one-year anniversary, I searched my heart and realized that a child no longer seemed like an intrusion to my life plans, but a welcome addition. I think leaving that crack in the door open for God through practicing NFP had something to do with this change of heart.