It is the one maternal feeling no mother wants to experience, the ultimate in parenting taboos: admitting (whisper it) that life might have been better before you had children. Now new research purports to show that starting a family doesn't make parents any happier than their childless counterparts.
A book out next month will cause controversy by suggesting that parents exaggerate how much better off emotionally they are with children around. Nick Powdthavee's The Happiness Equation paints a bleaker picture of parenthood than most parents would own up to recognising.
His findings will unsettle those parents convinced their children enrich their lives. But Dr Powdthavee's views may actually chime with more mothers and fathers than a quick glance around your local park would suggest, according to the magazine Psychologies.
Far from turning their lives into one long treat, say mothers in an article for the monthly, having children left emotional scars and endless worries that turned their lives upside down. Marsha, 50, described being "locked in a daily battle" with her son, who left home at the earliest opportunity, while another, Laura, 40, said she "missed the creative output" of her former life.
Descriptions of constant struggles with children suggest that parenting has more downsides than permanent fatigue and loss of social life. "No group of parents, whether married, single, step or empty-nesters, reported significantly greater emotional wellbeing than non-parents," found Robin Simon, professor of sociology at North Carolina's Wake Forest University. "Of the three major components of adult life – employment, friendship and parenthood – raising children is the only one that doesn't promote wellbeing."
Although most parents would claim that children enhance their lives, Dr Powdthavee, a behavioural economist at the University of York, believes this is only because "there is a discrepancy between what we think makes us happy and what happiness data shows actually makes us happy". He added: "When you measure how happy parents are on a happiness index, they report either an insignificant difference in happiness or lower levels of happiness compared with non-parents."
His findings mirror a wealth of sociological and psychological research conducted over the past four decades. "What's surprising is that everybody finds these findings surprising," he said. Yet mothers – and fathers – will often go to great lengths to hide the fact, even from themselves, that they find their children difficult. No parent we approached would say on the record that their offspring had made them unhappy.
Of the 1,400 or so mums and dads in Britain who blog about their lives as parents, few dwell solely on the negative. Chances are they want to avoid the fate of Ayelet Waldman, the American writer who last year admitted she loved her husband more than her children in Bad Mother: A Chronicle of Maternal Crimes. Her confessions prompted scorn, cyber-abuse and harsh public censure, from which she has yet to recover . Some readers told her they were reporting her to the authorities, because she should have her children "taken away".
Sociologists blame today's parenting struggles on the cult of parental perfection. "In the past 20 years or so, parenting has taken on this crazy emotional investment, popularly referred to as helicopter parenting, in which children are at the centre of their parents' lives," Dr Simon said. "Our parents wouldn't have dreamed of spending so much time with their kids."
Parents spend three times as many hours on activities with their children as they did a generation ago, according to research published this spring by Oriel Sullivan, a sociologist at the University of Oxford. Educated mothers put in most time, arguably to compensate for absences from the home.
If reading this has made any parents among you start worrying, then the American economist Bryan Caplan, from George Mason University in Fairfax, Virginia, has a simple solution: back off. "If you enjoy reading with your children, wonderful. But if you skip the nightly book, you're not stunting their intelligence, ruining their chances for college or dooming them to a dead-end job.
"Watching television, playing sports, eating vegetables, living in the right neighbourhood: your choices have little effect on your kids' development, so it's OK to relax." He also pointed to studies that show parents overwhelmingly do not regret having children: 91 per cent said they were happy with their decision, compared with 24 per cent of childless couples.
Dr Powdthavee, who is getting married next year, said he hoped to become a father. "The thought of children makes us happy. Plus, we're hardwired to reproduce. That fact has nothing to do with happiness."
The August issue of Psychologies is out on 7 July
Thrilling, exhausting, funny ... daily life on the motherhood rollercoaster
'I love the responsibility I have for this new life'
Sonoko Obuchi, 28, graphic Manga artist with two-year-old daughter
"Yoshika took me to the next level of life happiness. She has given me a closeness in my life I've never had before. I love the responsibility I have for this new life – it's up to me and her dad, Danyul, how to love her. It's an unconditional love. I don't need any reward. The reward is Yoshika. I have never seen my parents smile so much. Seeing Danyul become a dad is a beautiful thing. Hearing Yoshika say 'I love Mummy' was so great, so was breastfeeding, feeling I was giving life to her."
'I find it much easier now that we can have conversations'
Maria, 46, freelance journalist with two teenage sons
"There is tremendous pressure to conform to this career of motherhood. It wasn't until I made the children fit in to my world rather than me fitting in to theirs that I began to be happier. I'd been trying to be like the yummy mummies who subjugated their lives to their children's. I've always loved my boys, but I find it much easier now that they're older and we can have interesting conversations. I would have been happier if I'd worried less about making everything perfect. Mothers should settle for 'good enough'."
'Mothers feel guilty that they are not doing enough'
Emma Tolhurst, 37, business consultant and mother of three
"Society puts a lot of pressure on women to be the perfect mum. There's this feeling that children are going to solve problems and create this wonderful joy, when in fact we are human beings. There's a balance of being unhappy and then feeling happier when it's going really well. Mums can feel guilty that they are not doing enough for their children and anxious over their future. I had moments of being unhappy, but not for long, because we wanted children."
'I worried that we didn't have the connection we should have'
Marsha, 50, a single mother whose son left home eight years ago
"My son wasn't an easy baby. I told myself that it was because he was a boy, but I worried that we didn't have the connection we should as mother and child. There was a period, when he was aged seven to 10, when we seemed to click. Then it was as if he outgrew me. He started secondary school and wanted total independence. He threw temper tantrums, and told me I was evil and stupid for being a single mother. One weekend, I had to beg my mother to come and stay with him so I could escape before I did him real harm."
'Your heart grows bigger, and that means you're happier'
Joanna Moorhead, 47, journalist and mother of four
"Having children is enormously expanding. Your heart grows bigger, and that's got to mean you're happier. Kids give you what every life truly needs – someone you feel passionate about, something you'd do anything for, something you never waver from believing in. I have no idea how my life would have turned out without my girls. Motherhood is something I always knew I wanted. There's a depth that wouldn't have been there, a depth that has the potential for great, unrivalled happiness."
'I wish I'd followed my instincts instead of giving in to pressure'
Laura, 40, graphic designer and mother of two
"I didn't expect my child to come with such a strong personality. I assumed because we are easy-going, carefree people that our baby would be, too, but she was demanding, sensitive and difficult. For the first time in my life, I felt completely out of control. I wish I'd just followed my instincts more instead of responding to pressures from my husband, my mother and baby manuals. It's easier now both children are at school. Family life is calmer and more organised. But I miss the creative output that is such a huge part of who I am."