Just a few, short years ago, Jacinta Tynan's friends were career-driven, party girls who thought nothing of dancing until dawn, or taking off on a spontaneous weekend away. Now, thanks to their growing brood, these same friends are more likely to stay home discussing the minutiae of teething and toddler ballet than promotions and pay rises.

"Sometimes, I look at friends with babies and think they've lost the plot," muses the journalist. "They used to be carefree women, and now they're obsessed with bedtime, and cutting sandwiches up into little squares."

Jacinta isn't alone in feeling shunned by her baby-toting friends. In fact, one of the biggest issues among women today isn't boardroom bullying or relationships, it's the split between women who have children and those who don't, explains social commentator and psychologist Hugh Mackay.

"As the birth rate falls, parents are becoming more preoccupied with their children, leading to the emergence of 'helicopter parents,'" he says, referring to parents who hover over their children constantly. "They spend all their time trying to please their children, to keep them happy. Non-parents find this tedious, and a split opens up."

For their part, mums say they feel undervalued and misunderstood. "Being a mother is more demanding than any job I've ever done," argues mother of two, Claire Tickle. "It upsets me that there's no recognition that what I'm doing is important or valuable."

With a recent report by the Australian Institute of Health and Welfare* finding that one in four women will now remain childless, it seems the baby gap isn't about to close any time soon. So we asked two women to give their take on how having children has changed their friendships - and if they can ever get back to their pre-baby bonds.

"My two children are my world"

Claire Tickle, 30, from Sydney, worked as an office manager before becoming a full-time mum to two-year-old Emily and James, eight months.

"Since having children, a chasm has definitely opened up in some of my friendships with women who don't have kids. Recently, a friend asked us to come to Fiji for her wedding and didn't understand why I wouldn't leave my children with a $5-a-day nanny we'd meet on our arrival. These situations make me feel I'm being viewed as precious, when I'm just being a responsible parent.

"My children are my priority and, from 7am to 7pm, my entire day is organised around activities with them. If a friend comes over for coffee, I might still need to cook some baby food or fold washing. Admittedly, I feel a little rude, and they often comment that I'm distracted or don't sit down and chat anymore, but what they don't realise is that I'll pay for falling behind by having more work to do the next day, or struggle to catch up in the evening, when I should be resting.

"When kids are little, you shouldn't spend all their waking hours doing chores - you need, and want, to spend one-on-one time with them. Three days after my daughter was born, a girlfriend, who doesn't have children, came over at 10am and didn't leave until 8.30pm. Rather than cooking dinner, which would have been a great help, she just wanted to hold the baby, who cried when held by anyone but me or her dad. I didn't want to be rude and say that I was feeling tired and shell-shocked, but I really just needed to be alone with my newborn.

"Being a mother is more demanding than any job I've ever done, and friends who don't have kids can't seem to understand that I'm exhausted, and no longer feel like going out and partying until the wee hours. When your baby is a few months old, you need to be in bed by 7pm or 8pm because you're going to be up all night. Just the other day, one of my friends said, 'Do you remember when you used to be working and would get that overwhelmed feeling when you were really busy? That's how I've been lately.' She was totally unaware of the irony - I mean, when you're a mother at home on your own with two children, you soldier on feeling overwhelmed almost every day, partly due to sleep deprivation.

"Older mums turn parenting into a career"

Jacinta Tynan, 37, is an author, columnist for The Sunday Telegraph in Sydney and presenter with Sky News.

"When my school and university friends started having babies, I responded with interest to their many baby stories because I wanted to be supportive, and was genuinely happy for them. But after hours discussing mastitis and teething, I wanted to be anywhere else. I call it the 'baby gap'; no matter how much I tried, as a non-mum I found it hard to relate to a baby's wind or sleeping problems. On one occasion, when some friends brought their toddlers along to a girls' lunch, I excused myself after only half an hour to do something more enjoyable with my precious time off.

"I realise it's important they debrief with other mothers, but it's hard for me to relate to this bonding experience, so it's best I do my own thing. I have the greatest respect for mothers - I'm awestruck by the dedication and sacrifices made by my friends who are mums. It's beautiful watching them with their children and seeing how well they're shaping their babies into confident, well-rounded little people. It looks incredibly demanding, but I also think there's a danger that older mums turn parenting into a career, so that it becomes their entire life and they lose a little perspective.

"When I hear a friend is having a baby, I often think, 'There goes another one I won't be able to talk with for a while.' I still value those old friendships, but, obviously, our lives have gone in different directions and it's inevitable that we have less in common. I have actively sought out a new group of single friends because I accept that my mum-friends are no longer able to be spontaneous, and do the things I like to do, such as going for dinner or a weekend away at the last minute.

"I sometimes look at friends who have babies and think they've lost the plot - they used to be carefree women and now they're obsessed with bedtime and feeding timetables. Trying to have a proper conversation can be a little frustrating - it's not long before the baby starts crying or eating dirt, and you've totally lost your train of thought.

"I end up summarising my life in point form: here's what's happening with my personal life, my job and my writing. Meanwhile, we discuss everything about the baby in minute detail. I understand their life has changed, but it's a little disconcerting when a new mum makes the conversation all about her and forgets to ask how I am doing.

Read more about the baby gap in the December issue of marie claire.