The one job I never imagined having is the one that I've held for the longest. When I had two very small children and was planning a third, I quit my job at the London office of an American bank and became a stay-at-home mom. Although I wrote while I was home with my sons, I spent most of my time taking care of them. This decision ran counter to everything I was raised to believe in the 1970s and '80s and everything I had done to prepare myself for adulthood.

In my world, if you went to school alongside the boys, and then worked alongside the men, you didn't give it all up because parenting small children while working full time turns out to be really tough. But give it up I did.

I was far from alone in my ambivalence about melding my demanding job and my young family. Nationally, attitudes about working mothers with young children are still deeply conflicted, with only 16 percent of adults believing that the best situation for a young child is for a mother to work full time. One-third of Americans believe the best thing for a child is a mother who stays at home, and 42 percent believe the ideal situation is for a mother to work part time outside the home.

The decision to stay home or stay at work is based on a deeply personal confluence of factors. I don't believe that one woman can suggest what is best for another. Speaking only for myself and taking a backward glance, here's what I wish I'd known before I decided to be a stay-at-home mom.

1) My confidence would take a big hit

Entering adulthood, I thought confidence was something that came from within, that our sense of self was developed in the rocky shoals of childhood and adolescence. While social confidence or feelings of competence might be firmly established by college graduation, I soon discovered that professional confidence is a voracious beast that needs to be fed a regular diet of success. As a stay-at-home mom I had nothing to feed this glutton, which soon went into terminal decline.

Even as I became more secure as a parent, more sure that I could successfully guide three boys from infancy to adulthood, I found myself increasingly less secure in my ability to accomplish things outside the domestic realm. My confidence took hits from all sides. First, there was the feeling that the working world had moved on and I had become dated. Second, there was the fear that no one would take someone whose career description was "mom" very seriously. Finally, I discovered when I went back to work after a couple of years and a couple of sons, everyone was so incredibly young. The people who were my age and had stayed at work had moved on well beyond me.

My confidence took another hit from an unexpected quarter. When your kids are tiny, you don't foresee the day when they will see you as something other than just their parent. Yet the day arrives when they remark positively on a mom who is a teacher, an executive, or a doctor. There is nothing quite as demoralizing as trying to convince your kid that you had once been something, done something. That you had once mattered in some very small way in the larger world.

2) My world would shrink

One of the greatest joys of being a stay-at-home mom is the rich community that exists among parents. Friendships can be deep and abiding and, if we are lucky, last many decades after the children who brought the friends together are out of the house. But let's be honest. Most of our parent friends will be moms, close to us in age, and because of the way housing and schools work, close to our socioeconomic background. Staying at home with kids can lead to a situation where more and more of the people we come into contact with are like us.

The dismissal that stay-at-home moms get is not great from other women, but it's far worse with men

Work, on the other hand, more often broadens our world. An office may be full of men and women of all ages and backgrounds. Working is more likely to bring a flow of new and different people into our lives far outside the bounds of the other parents in our kid's grade. Inhabiting the working world brings us into contact with a wider circle of people. Becoming a stay-at-home mom can throw that process into reverse.

3) I would cringe every time someone said, "So what do you do?"

Identity and work should, in a perfect world, each be standalone parts of our lives. But we don't live in a perfect world and so often find ourselves judged on what we do for a living. I love meeting new people but came to dread what I knew would be one of the first questions every time I met someone. Sure, you can talk about volunteer work, or what you used to do, or what you hope to do, or you can just shout, "I do nothing. Do you hear me? Nothing." But very soon it becomes clear that none of these things hold people's attention for very long. Who wants to be only what they once were?

The quick dismissal that stay-at-home moms get is not great from other women, but far worse with men. I've found that women love to find common ground with each other. But meet a man in any setting, tell him you stay home with kids all day, and, unless he does the same, you have 60 seconds in which he will commiserate about how tough his Saturday afternoons alone with his kids are, before moving on to talk to someone else.

4) I would feel as though I had not set the best example for my kids

One of the abiding concerns of some stay-at-home moms is the fear that they are not setting the best examples for their daughters. By not using their hard-earned education in the manner it was intended, they feel they are giving their girls the message that the rules are different for women and that the hard work we expect of our girls might not be all that necessary. I thought I got a pass, at least, on this one. I have three sons, and so I had imagined the message about men and work lay at my husband's feet. Oh, how wrong I was.

Whether in a classroom or in an office, I want my sons to believe that the women among them are every bit their equals. Yet despite once holding the same exact job as my husband, the message I gave my sons was that men and women had different responsibilities, and while both were challenging, one used education and was financially rewarded and the other was not. It was up to me to help inform their views of women in every aspect of their lives. There are no passes in parenting.

5) Staying at home with young children is exhausting

Before I left my job, my husband and I would leave the house together every Monday morning with a huge sigh of relief. For the next 12 hours we would work, read, eat, and travel, without the constant demands of two children under 2. During the day I would walk outside and grab a sandwich with a colleague or run a quick errand on my own. It was a blissful break from the House of Toddlers that I inhabited on the weekends.

For anyone who has spent most of their career working at an office where bathroom and coffee breaks are of your own design, the relentless pace of life with small children can be far harder than anticipated. Colleagues are happy to let you finish a phone call, email, or thought. Not so, small children. They wear you down and leave you drained with their constant need for activity and attention. No boss was ever so demanding.

(Staying at home does have its benefits, though. Pew Research shows that working moms get less sleep and less leisure.)

6) I would envy women who had found their own work/life balance

Envy is not a pretty thing. But seeing the working moms every morning at school drop-off, it is hard not to be a bit wistful. For me it started with the outfit. Yoga pants and sweatshirts feel great until you look at a woman who has done her hair and is wearing adult clothing. It is not simply the superficiality of appearance but rather what the outfit signifies. It was hard not to feel that I had let an important part of life slip away.

It is a lot easier to become a stay-at-home-mother than to stop being one

Working moms made me feel bad about myself. I did not feel contempt for working moms (in the myth the press likes to fuel) but rather envy. They had figured out something that had escaped me. Here were my contemporaries, women of the same age and educational vintage. Yet they had made it work. They had great kids, who were usually my kids' friends. They had great careers. They had lives full of friends, and some of them even baked. That killed me.

7) I had forever damaged my financial future

One morning I walked into my boss's office and quit. He was gracious, polite, and encouraging. I hugged a few colleagues, emptied out my desk, and, by the following week, had moved from trading floor to playroom floor without a hitch.

Now just try putting that process in reverse. It is a lot easier to become a stay-at-home-mother than to stop being one. When looking at the cohort of highly qualified women who leave the workforce, only about three-quarters return to work at all. And among those, fewer than half return full time. As Sylvia Ann Hewlett explains, "Off-ramps [leaving the workforce] are around every curve in the road, but once a woman has taken one, on-ramps are few and far between — and extremely costly."

Staying home is a massive economic risk for almost any woman. By taking a career break of any substantial length of time, women risk a permanent impairment to their lifetime earnings.

Readers of my articles and blog have flooded me with stories of their regret at being stay-at-home moms. Many had spouses who lost their jobs and were unable to support the entire family on their now-diminished income. Some found that their husbands began to resent having the entire family budget resting on their shoulders.

The most painful stories that readers shared over and over are those of divorce. Each story is different, but all are a variation on the theme of husband and wife agreeing to split life's responsibilities and that agreement not lasting because the marriage did not survive. Women in their 40s and 50s find themselves facing a job market for which they are unprepared and a divorce settlement that is inadequate to support them. The regrets these women feel, at allowing themselves to become financially dependent while diminishing their own worth in the job market, are excruciating.

8) I would love the time spent with my sons

No one needs to tell parents that the days of having their kids at home are numbered. From their infancy it seems as though the universe switches to fast forward. The urge to spend this time with them is a powerful force that plays on both mothers and fathers. Pew Research found that half of all fathers say it is tough to balance work and parenthood; 46 percent of dads said that they did not spend enough time with their children (versus 23 percent of mothers). The time I spent at home with them was a gift for which I will never be able to express the full depth of my gratitude.

So, I do not regret time spent with my kids, not for a second. Were the years wasted? Of course not. But I regret leaving the workforce, almost every day. I wish someone had told me that it is possible to regret something and be glad that you did it all at the same time.

9) Everything has its price

I know, it's obvious, no free lunch and all. But the price of being a stay-at-home mom is not so easy to evaluate until after you have paid it. Leaving the workforce gave me the freedom to get things done as and when I wished. Sure, there was the tyranny of the school schedules and the needs of three small people, but in the end I had flexibility with my time that the workplace does not afford. I forfeited professional accomplishments to spend a lot more time with three of the people I love most in this world.

Many women quit their jobs because their after-tax income barely clears their babysitter's. When they look at the economics of working and combine it with the knowledge that they are missing the crucial baby years that they can never get back, walking away from a job starts to look like a real option.

The price of being a stay-at-home mom is not so easy to evaluate until after you have paid it

But I think both of these assumptions have within them great fallacies. The economic calculus of working may look bleak for a woman in the early or early-mid phase of her career when totting up the cost of child care. But unless she believes that her salary will be static, the calculation must include expected future earnings (which might be considerably greater) and the enormous potential cost to those future earnings of years out of the workforce.

It can be hard to see that the chaotic, I-cannot-handle-this years would be short, and soon life would be very different. Parenting intensity is U-shaped. There is a great deal of work or focus needed in the earliest years and the teen years, but in the overall scope of a lifetime of work, these periods are short. Leaving the workforce entirely is a solution with enduring consequences to a problem that turns out to be temporary.

It is all too easy, at the moment when we are making this decision, to believe we have fully considered the cost of staying home. But that cost is revealed over time, unknowable until it is being paid.

Lisa Heffernan is the author of three business books, including New York Times Business Bestseller Goldman Sachs: The Culture of Success. Her work has appeared in the New York Times, the Washington Post, and The Atlantic. She has been a guest on Today, the Katie Show, and Fox and Friends. Read more of her work at Grown and Flown.

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