Did you know that half the babies born to American women under 30 are born outside of marriage? Yes, half. Let that sink in.

More alarming, nearly three-quarters of the pregnancies to single women under 30 are not planned. Most say they didn’t want to have a child at that stage of their life, as documented by Brookings economist, Isabel Sawhill, author of “Generation Unbound,” based on hard data from a government survey of 20,000 women. And it’s not just young and poor minority women who regard pregnancy and marriage as separate decisions, or “drift” into one without the other, as Sawhill describes it. This new social norm is spreading fast and has moved up the class ladder to include all racial groups and many in the middle class.

Why? My sense is that the Millennial generation in the Trying Twenties has no “shoulds.” Individualism has trumped all the old social boundaries. So, what is our society doing to support it? Why do decades of well-documented needs for safe and affordable child care, longer maternity and paternity leave—even sick leave for God’s sake!—go down to defeat? On the day of celebration of mothers, how many solo moms feel overwhelmed? The sting of guilt?

I do. I was a single mother, product of an early divorce.

In the Sixties, paid maternity leave was no more than a week or two. I was expected to work until labor pains began, and I did. The two weeks I was allowed to bond with my baby were intense and joyful, but also strained by knowing that I had to wean her abruptly if I wanted to keep my job.

I was the primary breadwinner supporting my husband through medical training. On the bus to the office, I would hide behind my paper and try to swallow my sobs. I knew that the untrained sitters I could afford were no substitute for bonding with a mother. Working until 7 pm in the Women’s Department of a daily newspaper, I was stung by the irony that I and my young colleagues, who also left their infants at home, were writing to other women about how to improve their lives.

At the end of my child’s first year, I could bear the separation no longer. I quit my dream job. It was bliss to be at home to play with my daughter, mirroring and mimicking. I stayed up half the night writing to earn a living. But once my husband finished his training, he found another love and our family was severed by divorce.

In the scramble to survive in my mid-twenties, I lost sight of the most sacred trust with which we women are endowed. Our babies need our consistent nurturing for the first three months outside the womb, and ideally for at least the first year.

Through writing a memoir, I have reflected on the pain I caused my child. I find myself releasing my own deep sorrow and regret for the lost opportunities to soothe her in moments of her need, to play with her instead of watching the news to keep up as a journalist, to absorb her tantrums instead of having meltdowns of my own. Too often, she comforted me.

It’s not only absent working mothers who face this conflict, as they follow today’s well-meaning “Lean In” philosophy. Even when one works from home, there is tension between being fully present to a child emotionally and being able to sustain concentration on a deadline or a conference call.

I believe the most important choice we make as women is whether or not to have a child— and when. But young women in blighted communities like West Baltimore and Ferguson don’t have many choices in life. Without access to college or a decent job, and the pool of prospective mates dried up by crime and mass incarceration, the one source of love they can create is a child. For young middle-class women, solo parenthood is more often a choice, a way of asserting independence. They don’t think they need men, and credible partners in parenting are scarce here, too. Adult development is delayed in a long post-adolescence and wages have long been stagnant for middle-class men.

The main driver of solo motherhood is the resistance to marriage among Millennials.

Of course, many single mothers become devoted and raise healthy, loving children. But solo motherhood—especially when it’s unplanned—exposes children to an increased chance of poverty and limited education. The baby daddies often drift off. The mother must take on major responsibility for working to raise the child. Who is left to nurture and respond to the nuances of an infant’s emotional needs? For young mothers still struggling to find their own identity, it’s a balancing act weighted for a fall.

“When is it ok to go back to work?” It’s a question I often get at women’s conferences. “When can I have a life again outside my baby’s needs?”

The old comforting answer was, “Kids are resilient; they’ll adjust.”

We know differently now. Erica Komisar, a New York psychoanalyst with 25 years of experience as a parent guidance expert, demonstrates that “As early as three months, an infant is aware when his mother is not present.” In The Present Mother, her book-in-progress, she writes, “Whether she has gone to the office or is just running to the store, to an infant she has ceased to exist. At three months or six months, a mother who pulls away from a clinging infant inflicts unbearable pain on the child, since that is the very time babies first recognize their attachment to a separate mother.”

And yet that is exactly the time that business clamps down on the new mother and expects her to leave her child and make work her first priority. It’s not until a child is approximately 18 months old that she or he can hold the image of mother in mind and even begin to make sense of her physical absence.

“A mother who is present enough in those early months allows the child to internalize an image of mother and hold on to it for longer periods of her absence, without panicking,“ Ms. Komisar demonstrates. There is strong evidence that mothers who remain close to a new baby for the first year help to foster resilience.

The shift away from two-parent families is rattling the stability of our society. We see the signs in the disequilibrium of today’s offspring. Dramatic increases continue to multiply in attention deficit, aggression, and anxiety among children from four to 17.

Take it from a chastened single mother. The bond between mother and child is the most delicate and enduring in one’s life. It is the root system for a healthy society. Motherhood deserves to be chosen, planned, shared with a committed partner or family member, and supported by workplace policies that honor the present mother.

Gail Sheehy is author of the memoir DARING: My Passages