When Sheila Heti’s novel, Motherhood, was published in the US, many of the reviews opened with personal experiences. The book, which describes a female writer in her late 30s (in many ways indistinguishable from Heti) reaching a decision not to have children, is a sometimes frenzied, sometimes laconic, often very funny meditation on the ambivalent state in which many women find themselves in their late 30s, and has been received in a way that rather grimly underscores the themes of the novel: that a great many women take other women’s decisions about motherhood as a direct rebuke to their own. If a review starts along the lines of “when I had my first child … ” you know Heti is in for a rough time.

At 41, the author herself is no longer agonised; part of the purpose of writing the book was to get over the decision: “It’s a scary thing to look into,” she says. We are in a hotel in downtown Manhattan, where she is staying while visiting from her native Toronto. She is slight, her voice infused with a levity that has been lost in much of the commentary around Motherhood and that is a central quality of Heti’s writing, from 2005’s Ticknor, her first novel, to 2010’s How Should a Person Be?

Motherhood is in some ways a more avant garde project than the other books, somewhat formless, necessarily obsessive, rigorously limited to the question at hand, and at the same time by far the most mainstream of her novels. Ticknor, for example, is about the relationship between two relatively obscure 19th-century writers, William Hickling Prescott and George Ticknor. Even choosing to write about motherhood, or in Heti’s case the decision not to become a mother, is a source of anxiety and shame, and I say that as someone who has just written a book about having kids. “I had that feeling of embarrassment, too,” says Heti. “Like, am I really going to do this? And why? It’s such a huge, monumental, essence-of-life topic. We all have mothers. Why is this chick-lit? Or – I don’t know exactly what the feeling about it is.” She bursts into laughter.

When the novel opens, the Heti character is 36 and living with her boyfriend who has a child from a previous relationship and doesn’t want any more, but informs her she’s welcome to try to persuade him. Meanwhile she’s not even sure she can persuade herself. But – and this was part of Heti’s purpose in writing the novel – it seemed important not to sleepwalk through the decision.

“That was the one thing I really didn’t want for myself; which was to let it happen to me. And I think for a lot of people, that would be their preference. I have a friend who was like, I can have a baby, it’s no big deal, it’s just so burdensome the idea that I have to think about it. For me it was like, I don’t think I could live with myself if I wasn’t thoughtful about it.”

And yet for many women, it is a decision over which, I think, they assume they have limited control. “Yes, they say the superstitious thing of ‘let life happen’. Well, I’m sure those women didn’t do that in every aspect of their lives. Those are people who know how to get what they want. It’s hard to say you don’t want it. It’s like you don’t even believe yourself when you say that.”

Some of the criticism around Motherhood has taken on a chiding quality and of course, as Heti points out, “women are as bad as men about all this policing”. Rather than simply railing against the impertinent judgment of others, Heti, in the novel, takes the much more subtle approach of mourning what is lost when someone finds themselves at odds with the mainstream. “There is a kind of sadness in not wanting the things that give so many other people their life’s meaning,” she writes. “There can be sadness at not living out a more universal story – the supposed life cycle.”

There is shame attached to not wanting children, Heti says. But I also felt shame for the fierceness with which I wanted kids. “Maybe there’s a basic shame women feel and it just attaches to anything,” she says, laughing. “It’s kind of how I feel about anxiety; when you’re an anxious person like I am, I realised at a certain point, it’s not the thing I’m feeling anxious about that is making me anxious, it’s that I have a feeling of anxiety and it attaches to whatever it can. Maybe if we both feel shame it’s because it’s shameful to be a woman. Whatever you choose you feel shame.” She pauses and drily adds, “I wonder if it’s ever going to change, or if women will feel that way until there are no humans ever.”

¶

For many years, Heti worked remotely as an editor and writer for the Believer magazine, the literary journal based in San Francisco. She functions best, she says, when she has more than one project on the go and can find relief from one by picking up another. “I just like working. And each is a different kind of work. Sometimes you can’t write a novel for weeks and weeks, but it’s good for your self-esteem to work on something else.” She gave up the Believer when she started putting together Women in Clothes, an anthology of photos, interviews and stories that amounted to a “conversation among hundreds of women” about why we wear what we wear, which she assembled with two writer friends, Heidi Julavits and Leanne Shapton.

Every one of Heti’s books has diverged radically from what came before, and yet her work is recognisable for the consistency of its humour, and for her desire to get at the truth via unconventional means. She is suspicious of the boundary between fiction and non-fiction. The details of Motherhood are largely autobiographical but the register is fictional. “I don’t know what that line is between fiction and non-fiction that other people have in their minds, but to me when I’m writing it’s just like whatever the next sentence should be is the next sentence. It’s not this artificial division.”

Heti is very firm about what works in her writing and what doesn’t. After Ticknor was successfully published in Canada it was picked up by Farrar, Straus and Giroux in New York. Her American editor, however, rejected her next book, what would turn out to be the much praised How Should a Person Be?, a philosophical novel in which Heti took real conversations she’d had with her friends and wove them into a book that, once again, only loosely met the definition of fiction. “He read an early draft and didn’t want it. Didn’t like it or understand it. It looked different than the book [that was published] because it was years away from being done, but he didn’t like it, so that was the end of my illustrious, very short FSG career.”

When a powerful editor says something doesn’t work, what gave her the courage to disagree? “I’d been working on it for so long, I just knew he was wrong. In the case of that book I had my friend [the artist] Margaux Williamson say he’s wrong. I had support. If it had just been me all alone I might have been more tempted to think, oh, he’s right and I fucked up and wrote a horrible book. But I just kind of knew that he was wrong. He was like, ‘Put it in a drawer’, and I thought, ‘Fuck you, I don’t want to put it in a drawer.’” She laughs. “I knew because it’s the only thing I know: what to do with my books. Everything else in life is a mystery, but I feel an amount of certainty about that stuff.”

There is a good section in Motherhood about the value of failure, not in the Samuel Beckett sense of fail again, fail better, but in the true wildness of failing in a society that puts so much value on success. “Only in our failures are we absolutely alone,” writes Heti. “Only in the pursuit of failure can a person really be free.” She concludes, “Losers may be the avant garde of the modern age.”

She finds failure interesting. For a while, she wondered if she should move to New York, but “I just write better in Toronto than I do anywhere else”, she says. She is wary of what living in New York does to people, “where the bourgeois ideal is so oppressive, and everywhere you look is what you’re supposed to be living up to. The food you eat, everything. There’s no space where you’re not performing. In your bedroom, that lamp or whatever. I like that idea of pursuing failure. It’s just such a relief.”

Heti’s writing has been successful. Her novels are the subject of long, serious disquisitions in the New Yorker, where How Should a Person Be? prompted one critic to say of the author: “This talented writer may well have identified a central dialectic of 21st-century postmodern being.” But she has experienced failure in her personal life, she says, notably a short-lived marriage in her mid-20s. She has lived with her boyfriend Lucas, a criminal attorney, for many years, but for a long time she considered her ambivalence towards wanting to have children as an abject failure.

She thinks differently now and the way she talks about it is very persuasive. “If there is a longing for babies that women feel, as I’ve heard it described, this very deep yearning, that must be biological – then wouldn’t not feeling it also be biological? There’s always been people in society who don’t have babies; this idea of alloparents. It’s a Margaret Mead, anthropological idea, of all these cultures throughout history that have had so-called alloparents, people who help parents raise their children, but are not themselves parents. Aunts, uncles – there is a need in society for people without children. So if there is also a need for children, then maybe some people are given that urge and some people are not. It’s symbiotic.”

And yet, as she points out, everyone is subjected to the same “pressure to do it”, so much so that “there is this feeling if you decide not to have children where you want to just tell people, so they stop expecting that of you. And then you also want to tell yourself, so you don’t go on feeling like you’re expecting it of yourself, or like you have to constantly contend with it.”

Somewhere in those years between 35 and 40, what Heti realised she really wanted was to throw everything she had at being an artist. Her writing explores the far reaches of experimental fiction, an all-consuming and energy-inefficient way to write, given the amount of material she ends up throwing out. One of the books she had on the back burner while writing Motherhood grew out of Heti alphabetising her diaries – “so it’s like 120,000 words, but the sentences are arranged in alphabetical order. So, all the sentences that start with a, and then b.”

How do you even germinate an idea like that?

“It came out of a really specific place. I keep diaries, and I keep them on my computer, and I was wondering how much repetition there is in my thoughts. Am I having the same thoughts this year that I was having six years ago? Has anything changed? So I thought that the way to find out would be to see how many times certain sentences repeat; how many times did I write ‘I hate him’ or whatever. So I loaded them into Excel and did a whole bunch of tech stuff. It didn’t end up answering that question for me, but that was the start.”

She has a publisher interested, but Heti isn’t yet sure whether “I want this in the world, or just for me. I’ve sent it to friends.” This is the grey area out of which so many of her books emerge, a determination to write herself out of an indeterminate state, or what in Motherhood she calls “mush”. “Just give me a form,” she says now. “Let my life have a form. Any form.”

It is strange to consider that something as interior and literary as this novel might be used as self-help, but I think it will. It finds the commonality of experience on both sides of the baby divide, in a way that, given how toxic and reductive the subject can be, restores dignity to both. “I hope so,” says Heti. After all, she points out, a novel “doesn’t have a stake in your life like everyone else you know does.” She smiles. “Who should help you if not books?”

• Motherhood is published by Harvill Secker.