I catch her eye across the pew and smile. Her stomach is starting to swell, slightly. After Mass she rushes over, excited and chatty. “How are you?” I ask.

She glows, bursting with good news. “Everything is great. Eighteen weeks now! We have the big ultrasound on Friday.”

I think of all their losses, their years of yearning. The prayers I offered for them as I’ve pleaded for so many couples struggling with infertility: “Please God, grant them this desire of their heart. Please God, let this be.”

I grin back at her. “I’m so happy for you! So are you finding out?”

The question everyone asks expectant parents. Are you finding out if the baby is a boy or a girl?

She shakes her head happily. “No, we’re keeping it a surprise.”

I think back to our first two babies, the ones we kept surprises. The delirious delight after delivery to hear my husband declare, “It’s a boy!” as I pulled a screaming, slippery warm baby to my chest.

I imagine the child we lost to miscarriage. The one we never got to know.

I picture our third son, the first one we found out before birth. The boy I fell in love with as soon as I saw him on the ultrasound screen (though everyone thought we hoped for a girl).

I remember our twins who were born prematurely, our daughters who lived only a few days, who took their last breaths in our arms as we let them go back to God. The girls we got to find out so little about.

I place my hand on my own rounded belly, the new baby who kicks and pushes within me. The one we can’t wait to meet.

And I marvel at the fact that all of our children remain mysteries.

Even as parents care for every inch of children’s bodies while they are young, even though we share each day while they live under our roof — we are always finding out who they are.

Our children are not ours. They are God’s: the work of the creator’s hands. God knit them together in darkness. God breathed life into their lungs. God knew all their days before they were numbered.

God is the only one who knows them fully. We have only begun to find out.

According to a study from Harvard Medical Center, 58 percent of expectant parents plan to find out their baby’s sex. But no medical test or magical formula can reveal who our children are becoming.

The calling to parenthood is an invitation to keep finding out. To honor our children as gifts from God, mysteries that keep unfolding before our eyes each day.

One of the best parts of life is mystery. I missed this in my youth, when I thought adulthood would bring certainty, clarity and control. Instead I find that God invites me into deeper mystery, the sacred surrender of unknowing.

This is part of the adventure of family life. Even my husband whom I have known for nearly two decades remains a discovery to me. Our children are the same. Delightfully enigmatic, we are finding out.

“At present we see indistinctly, as in a mirror,” writes St. Paul. “But then face to face. At present I know partially; then I shall know fully, as I am fully known” (1 Cor 13:12).

What joy to be fully known. But what joy, too, to discover all along who God is calling us to be.

Fanucci, a parishioner of St. Joseph the Worker in Maple Grove, is a mother, writer and director of a project on vocations at the Collegeville Institute in Collegeville. She is the author of several books, including “Everyday Sacrament: The Messy Grace of Parenting,” and blogs at MotheringSpirit.com.