When you’re the mother of a newborn baby nobody bats an eye if you take a year off work to look after your son. But try explaining to your boss that you’d like a year off to care for your strapping teenager. Yet that’s exactly when today’s mums say their children need them most — and more and more are cutting back on work to do just that.

Whether they are television presenters like Carol Smillie and Janet Ellis, or less well-known women juggling stressful careers, mothers are finding that waving goodbye to baby on Monday morning was child’s play compared to leaving older offspring behind. When homework and hormones start to appear on the scene only teenagers’ parents, it seems, will do.

Smillie, a mother of three, aged 11, 8 and six, was rarely off our television screens when her children were tiny, travelling all over the country to present Changing Rooms and, before that, Holiday on BBC2. It meant long hours and sometimes up to five nights away at a time, but in those days, she says, it was she who suffered from separation anxiety, not her children. “I felt very guilty about it but Christie (her elder son) was absolutely fine,” she says. “He got used to it very quickly and he was very happy with Daddy or our nanny.”

She would find it more difficult to do that now. “It was easy then, they just needed a cuddle and a bottle and a lot of people were willing to do it because everybody loves a baby. Now it’s more complicated, they don’t want their mum not to be there,” she says.

Her eight-year-old son Robbie, for instance, is “going through a bit of a clingy time and just wants me to be around — or at least know where I am and when I’ll be back. It’s nothing serious but I think emotionally they do need you more as they get older”.

For that reason she picks and chooses work that suits family life. “I couldn’t do a live daily show from London now — it would be too big a commitment and too complicated,” she says. “Those few minutes when they get home from school are the most full-on of the day. They are all bursting with a story to tell, with news of their day and they want to tell you at once.”

It’s a viewpoint many mothers of older children are now acknowledging. Magazine editor Joani Walsh never had a qualm about leaving her child to work full-time when her son Ronan was tiny, but last year she gave up her job and went freelance so that she could spend more time with Ronan, now 15.

“He may not say that he is happier that I am here but he does say that we talk a lot more and I know I have more time to do the ordinary everyday things with him that I never could before,” says Walsh.

“There was a practical side to it as well — Ronan had flat feet and they needed sorting out and he had braces on his teeth which had to be adjusted every few weeks.”

So why do children need us more as they get older? Suzie Hayman, a relationship counsellor and trustee of the parenting charity Parentline Plus says that more than half of all the calls for help they receive come from the parents of teenagers.

“When they are tiny children need care, they need feeding, guiding and teaching — when they are teenagers they are trying to find their own way in the world. They don’t need care in the same sense, what they need is for you to be there for them,” she explains.

“Remember when they were toddlers and would run away from you but still keep turning back to check you were still there? Teenagers are identical. They need to make their own mistakes, but they need to know that you are there to pick them up, dust them off and kiss the bruises. When I talk to people looking back at their teenage years their biggest complaint is that parents weren’t there for them, either physically or emotionally.”

It’s not a mistake Janet Ellis has made. When her first daughter, the singer Sophie Ellis-Bextor, was tiny, Ellis worked flat out as a Blue Peter presenter and continued to work all hours when her other children, Jack, 18 and Martha, 15, were babies. She imagined that life would get easier when they were teenagers but then found that they needed her in a different way.

“Little children are, I think, in some ways quite promiscuous in that as long as they are loved and you have chosen the right person and things like their shoes fit — they are perfectly happy to be with someone else,” she says.

Older children are less happy with that and she admits that she has since turned down work in order to ensure that she is able to spend time with them. “When they were little I worked flat out and I was happy to — now I wouldn’t be so happy to. I’m lucky, I have a choice, but I wouldn’t reverse it.

“It’s a difficult time for them . . . it’s more than just having the right money for the bus. It’s the time they have to deal with huge things like the possibility of drug abuse, and dealing with sex for the first time. It’s a hugely vulnerable time.”

And, of course, there’s the pressure of exams. Lorraine Enstone, a teacher and mother of two boys, Charlie, 16, and Louis, 8, has delayed her return to full-time work not, she says, to look after the younger one, but to steer her older son through his last years at school.

“Louis was getting to the age where I could really, have gone back full-time, a couple of years ago,” she says. “But I decided there was no way I could do that with Charlie’s GCSEs coming up.

“It’s about being around to get them up in the morning, to make sure they have clean clothes — just being a presence in the house. It’s almost as if they go backwards for a bit — instead of you constantly ringing them to find out where they are, they start ringing you and asking where you are and when you’ll be back.”

So maybe these mums have got it right. As their teenagers’ childhood slips away and they prepare to fly the nest there’s a sense that this is a need all the more urgent for being fleeting. As Walsh explains, “I can’t put my hand on my heart and say, ‘Yes he’s doing better than he would have if I wasn’t here’ but I can say that if I hadn’t had this time with him then I would have regretted it for the rest of my life.”