But the "breast is best" mantra has unintended consequences. For some, it provokes guilt, shame and feelings of failure.

"I always felt like people were judging me," Sydney mother Kate Wild said. "There is still this idea in the back of your mind you're not doing the best thing for your baby because you are told ad nauseam that breast is best."

The Westleigh mother of two had every intention of breastfeeding when her daughter Poppy was born two years ago, but pre-eclampsia and a post-partum haemorrhage landed her in intensive care straight after the traumatic birth.

"I just didn't have enough supply to start out with and when I came home from hospital with Poppy, she was losing weight and she was really unsettled," she said.

After recurrent bouts of mastitis she saw a specialist and weaned Poppy. When her second baby, William, was born 3½ months ago, she breastfed for a few weeks before moving to bottles.

Ms Wild's feelings of guilt as she battled to breastfeed are not unusual. Indeed, journalist and mother Madeleine Morris says these stories are so common she was compelled to write a book supporting parents who agonise over giving their babies formula.

"The way it's been promoted to mothers, we feel like breastfeeding is the single most important thing that you can do for your child and if you don't do it then your child will end up sick, fat and stupid," said Morris, who breastfed her daughter for seven weeks but switched to formula when she could not produce enough milk.

In Guilt-Free Bottle-Feeding, Morris and co-author Dr Sasha Howard - a paediatrician and mother of two - maintain the pressure on mums to breastfeed is unacceptable, and that while breast milk is still the best option whenever possible, bottle-fed babies can grow up to be just as happy and healthy.

"I've spoken to women who feel guilty 30 years later for not being able to breastfeed their babies," Morris said. "I've spoken to mothers who persisted for months and months in excruciating pain and then finally gave up and said, 'I just wish that I could get that time back with my baby instead of looking at her and wincing and dreading her coming to the breast'."

Morris, an Australian-born, former BBC journalist who now works for the ABC in Melbourne, said the "breastfeeding at all costs" mentality has led to the benefits being heavily promoted while other complicating factors are downplayed.

However, Jennifer James, a lactation consultant and counsellor with the Australian Breastfeeding Association, said the pressure came from mothers themselves.

"This whole notion of someone else making them feel guilty is a nonsense. If you're a woman who feels very vulnerable who's desperately trying to find out how to breastfeed because nothing seems to be working, then any message about breast milk being best for babies and what they need to optimally grow is going to make you feel like a failure," Dr James said. "But the fact remains that breast milk and breastfeeding is the biological norm and that babies are born to breastfeed. Their bodies are designed to develop optimally on their mother's milk."

Dr James said the World Health Organisation recommended exclusive breastfeeding for the first six months of life and that 95 per cent of women are physiologically able to breastfeed, so most babies should not require formula. Topping up with a bottle could lead to a "vicious cycle" in which breast milk supplies diminish.

"The women who don't even try, they're the ones that tend to hit out and try to find someone to blame," she said.