Mums should keep score of chores - and have more sex, says a new book about the strains of parenthood. Kate Holmquistmeets one of the authors

If you want to put your marriage to the test, have a baby or two. Issues over who wakes up at 3am for the baby and who gets to sleep in can lead to bickering, sexual death and emotional insecurity - especially when it's Mammy who always wakes up and Daddy who gets to sleep in at weekends.

When Dubliner Cathy O'Neill (33), a lawyer, found herself in this predicament after moving to Austin, Texas with her Indian-born husband Mike eight years ago, she shared her concerns with her best local friends, Americans Stacie Cockrell and Julia Stone.

"Stacie would say, 'Ron and I never used to fight and now we bicker all the time. How are things with you and Mike?' I admitted that he was getting on my nerves because while we were both working, the buck always stopped with me as far as the baby was concerned. I had become a drudge. We realised that most new parents were having the same sorts of arguments."

The three mothers had never heard of a book about the seething undercurrent of resentment that affects many parents of young children and can even lead to marriage break-up. So with no previous writing or publishing experience, they decided to write one. Fast-forward to a year later, and O'Neill and her co-authors have published Babyproofing Your Marriage: How to Laugh More, Argue Less and Communicate Better as Your Family Grows (Harper Collins, £7.75 in UK). O'Neill and co are set to become household names through appearances on Oprah and the Today Show - not to mention what O'Neill calls a "lotto ticket" contract.

O'Neill, Cockrell and Stone have backgrounds in business and law, and their book takes a businesslike though humorous approach to negotiating deals between parents to come to a fair division of parenting responsibilities.

The book advises desperate new mothers to educate fathers by abandoning Daddy for a weekend to look after baby without back-up - and he's not allowed to call his mother. Mothers should also keep their partners happy with the occasional sex act, which O'Neill calls "the five-minute fix". And no, it doesn't require undressing.

But what's most intriguing about this trio of media goddesses is how they confidently drew up a business plan and marketed their confidential kitchen confessions in a way that had publishers panting to sign them up. Their approach included doing their own market research and producing demographics to show how many book-reading new parents were in need of such a book. Next, they wrote a chapter about sex after babies and a synopsis of the rest of the book. They sent the entire package off cold to agents whose names and addresses they found in the guide Writer's Market. Within a week, Richard Abate of International Creative Management responded.

"He has two young kids and said he'd felt like we'd had a camcorder in his bedroom. He told us that our proposal was the most accomplished, focused and saleable proposal they'd received in 18 months," says O'Neill.

The three mothers were flown to New York where ICM told them that they would be household names within the year with their motto "Damn you Martha Stewart". An auction followed among six publishers, with Harper Collins succeeding. O'Neill's parents, Mary, a family lawyer and Brendan, a property developer, were so excited they flew the entire family out to New York from Dublin to celebrate. "Only in America," they told their daughter.

O'Neill, who was pregnant with her second daughter at the time, embarked on the most hectic time of her life. It had taken the three authors six months to produce the proposal and the sex chapter. Harper Collins wanted the rest of the book within three months, a short deadline O'Neill swears she'll never undertake again.

Articulate and composed, O'Neill was head-girl at Loreto on Stephens' Green before studying law at UCD. After graduating in 1995, she worked for five years at McCann Fitzgerald in Dublin while conducting a long-distance relationship with her future husband, Mike, a lawyer whom she met while on an exchange programme at the University of Chicago in 1993.

Since marrying Mike and setting up home with him in Austin - a far more sophisticated oasis than she had expected considering it's in George Bush's home state - O'Neill says that she has grown to appreciate the confident American attitude toward success. She has also developed an American candour about personal issues - even though she is somewhat worried about how her father might react to the controversial chapter about mothers keeping fathers happy in the bedroom.

"Take the energy that you are about to put into cleaning and go upstairs and have sex with your husband," says O'Neill. She and her co-authors had come to dread what they call "the 10 o'clock shoulder-tap" because they were tired, preoccupied and didn't anticipate getting much pleasure from sex without the dinner and conversation beforehand.

It was only when interviewing focus groups to get material for the book that O'Neill realised how painful perceived sexual rejection is for new fathers.

"We knew sex was important to men but we were amazed at the level of anguish. Many were close to tears," she says. She was particularly affected when a new father said, "When your wife rejects you three times in a row, you have no idea how soul-destroying that is." Another man thought, "she doesn't love me any more." One man confessed that when he hasn't had sex with his wife in two months, he finds himself "staring at other women's asses" and he flirts more aggressively because he's looking for affirmation that he's attractive. "Sex was more than a physical need for men. I was really surprised to hear about how men felt in those kinds of terms."

Score-keeping by parents to keep each other in line is another of the book's recommendations.

After her first daughter, Kate (3) was born, closely followed by Maeve (1), O'Neill says she realised that a distance had grown between herself and Mike, who had developed a weekend obsession with fishing.

Cockrell and Stone confided that their husbands too had found weekend hobbies that took them away from family life - Stone's husband took up marathon cycling while Cockrell's husband decided to campaign for John Kerry, which led Cockrell to protest, "Who needs you more? Me or John Kerry?"

The three women came up with the concept of "score-keeping", as in, Daddy gets points for emptying the dishwasher and doing the shopping, but loses points coming home at 9pm when he says he'll be home at 6pm. Mammy gets points for letting Daddy go fishing and having sex with him.

"We wanted the book to be witty, funny, unsanctimonious and free of psycho-babble. Our basic question was: 'what has happened to our marriages?' Everything went into the gristmill and we had a few knock-down, drag-out arguments before we got there."

O'Neill never stopped working when she became a mother, while Cockrell and Stone decided to stay full-time in the home, although none of them is judgmental about the others' choices, O'Neill says.

The women believe that fathers and mothers are fundamentally different. One night, O'Neill and her husband went out in the car to get a video, leaving their eight-week-old baby alone asleep, because O'Neill forgot that they had a baby. In the video shop, she remembered, panicked and headed straight back to the car, while Mike said - "hang on, let's get a video first. Don't worry. She'll be fine." O'Neill started up the car and told Mike to find his own way home. She says the experience taught her that fathers don't have that intense connection with their babies that mothers do, a view that many fathers might disagree with.

O'Neill thinks that fathers should not be expected to be mothers, but should be aware enough of the demands to offer support. "In our research, we found that a lot of women basically wanted to be married to other women, because they wanted their husbands to think and act like women. Your husband is never going to be like that - you have to take responsibility for your own needs and get much of your emotional support from other mothers, while at the same time making sure your husband keeps his side of the bargain and does what you ask him to do," she asserts.

The Harper Collins website has a husband-training video on it that O'Neill says she is uncomfortable with. "The book is not a girls' bitching session," O'Neill says. It's intended for parents to read together - perhaps a chapter a night while in bed - in order to find a way to discuss their feelings and negotiate a team approach to child-rearing situations that works, she says. (Although any parents of a new baby who can find time to read, never mind together, not to mention in bed, are already doing well.) The authors researched the book by conducting group discussions with hundreds of parents at book clubs, poker nights and even Bible study groups.

Once they got their list of problems, they tried out solutions themselves.

O'Neill says: "Everything in the book we've tried . . . it was intense. I wouldn't do it again!"