Of the many treatises written on the spiritual life in the Catholic tradition, there is one I visit annually, usually around Advent: The Reed of God, by 20th century English writer and mystic Caryll Houselander. In this work, Houselander examines the Virgin Mary as the model Christian disciple and missionary.

The general idea is that Mary, in her purity and virginity, is capable of allowing the Word to work in and through her. “It is emptiness like the hollow in the reed,” writes Houselander, “the narrow riftless emptiness, which can have only one destiny; to receive the piper’s breath and to utter the song that is in his heart.”

Beautiful as her mediations are, there is one passage that always makes me laugh for its forthrightness about how some Catholics, myself included, can struggle with Marian devotion.

“When I was a small child someone for whom I had a great respect told me never to do anything that Our Lady would not do; for, she said, if I did the angels in heaven would blush,” Houselander writes. “But even if I faced a blank future shackled with respectability, it was still impossible to imagine Our Lady doing anything that I would do, for the very simple reason that I simply could not imagine her doing anything at all.”

As a cradle Catholic, I remember Mary in the same way, as a figure who was always around in images on our walls, in statues and stained-glass windows in our churches and imprinted on the many rosaries scattered on end tables and nightstands. She was close by, but not completely accessible, almost frozen in a downward, contemplative gaze. Emulating her felt like an impossible task, as did drawing close to her through prayer.

It wasn’t until I became a mother that I began to more seriously engage in a relationship with Mary. To be sure, it wasn’t the images of her holding the infant Jesus that did the trick — any mother of young children, especially those of boys, knows that they never sit as serenely in their mother’s arms as Jesus did for Mary.

Instead, my deepening relationship with Mary was driven by something more primal, more biological in nature. I think it had to do with what medical anthropologist Dana Raphael calls “matrescence” — the physical, emotional and psychological transition to motherhood that a woman undergoes, and the accompanying re-orientation of her entire being in the world.

There is, undoubtedly, a kind of “hollowing out” of oneself that is attributed to virginity — a willingness to be sent where God asks and the forfeiting of natural goods for the sake of something greater. But motherhood, too, requires a hollowing out: first, the literal hollowing out of one’s womb to make space for another; but also the lifelong process of shedding one’s old self and putting on a new self for the sake of one’s children. What is amazing is that in God’s design, children help their mothers — both biologically and spiritually — to continually conform themselves to the mission and vocation to which God has called them.

The emerging science of motherhood sheds light on the biological connections between mothers and children ranging from the neurological changes that take place in a mother’s brain to the interaction of their two bodies at the cellular level. And it has been these realities, studied and experienced firsthand in my own changing physiology and psychology, that have helped me to understand why it is that we Catholics draw close to Jesus through Mary, and what it means to consider her our own mother. Far from being a distant and impossible-to-emulate model of purity, contemplation, and prayer, Mary is deeply involved and invested in our protection, thriving and destiny.

In a 2019 essay in Church Life Journal, Dr. Kristin Collier, an assistant professor of internal medicine at the University of Michigan, writes about the phenomenon of “microchimerism,” that is, “the presence of a small population of genetically distinct and separately derived cells within an individual.” Research reveals that fetal cells remain in a mother’s body throughout her life, long after pregnancy and childbirth. Far from simply floating around, these cells get to work by providing health benefits to the mother, including helping her to heal from a caesarean section and warding off breast cancer.

When I think about this reality in terms of Mary and Jesus, it drives home the intimacy they share as well as the idea that they work together in tandem. Mary is not only considered a tabernacle for the nine months that she carries Jesus; she is always carrying him in her body, even at the cellular level.

What’s even more fascinating about the science of microchimerism is that a special kind of healing by fetal cells takes place in mothers’ hearts.

In her new book, Mom Genes: Inside the New Science of Our Ancient Maternal Instinct, Abigail Tucker explores the latest research into this phenomenon, particularly the ability of fetal cells to help some mothers recover from an often-fatal condition called “peripartum cardiomyopathy,” which can strike just-delivered mothers. Researchers in New York City’s Mount Sinai laboratory are trying to unlock the mystery as to why 50 percent of mothers spontaneously recover from the condition. Their best guess is that the fetal cells from the baby rush to the mother’s heart, multiply and transform into cells that function like heart muscle cells.

What could be more helpful in understanding Mary’s role as mother and mediatrix than this? We believe that Mary and Jesus speak “heart to heart,” as Sts. Francis de Sales and John Henry Newman have characterized prayerful conversation. If this scientific theory of heart repair is true, we say with even greater confidence that Our Lady’s pierced heart is truly healed by her son’s saving act. And we can be assured that his Sacred Heart and her Immaculate Heart beat together as one, and they eternally heal and console one another in a mutual act of love.

As Catholics, we also say with confidence that Mary is our advocate, meaning that our prayers for her intercession have a real effect on her Son. This is often attributed to the idea that no child could ever refuse the requests of a mother he loved so much.

But there is also scientific evidence that a mother’s voice directly affects her child’s brain and behavior. Maternal-fetal science has uncovered that as early as 16 weeks in utero, a developing baby can hear his mother’s voice and that the sound of her voice is largely responsible for his subsequent linguistic development. In addition to being able to distinguish her voice from among others, a child’s breathing, heart rate and the thickness of the auditory cortex in the brain are directly affected by the sound of his mother’s voice.

Given this evidence, how could we ever believe that Our Lord would hear his mother’s voice and fail to respond? The Word is moved by the words of his mother. That dynamic has been written into his own incarnation.

When I was preparing for the birth of my firstborn son, I was focused in word, deed and prayer on how God would ask me to shape him into the man he was meant to be. My focus was on his mission and how to help him discover it. But as I prepare to welcome my second son, this new maternal science has helped me to realize that it is my children who have materially changed me for good and will be at work over the course of my own lifetime helping me to better understand my own mission and vocation.

How generous that in God’s providence the mission of motherhood has built within it a mutual support system. We know this in faith through the relationship we see between the Blessed Mother and her son; we are now just beginning to understand how grace builds on nature, thanks to the emerging science of motherhood.

Elise Ureneck is a communications and public relations professional who writes from Boston. She is a regular columnist for Catholic News Service and founder and principal of Credendi Communications. Her previous roles include associate director of the Church in the 21st Century Center at Boston College and the executive director of The GIVEN Institute.