When a baby is born, everyone wants to know its weight. But my baby’s size, or lack of it, was an issue for six months. She wasn’t putting on enough weight, health visitors said. Other babies’ growth charts climbed steadily, but not Alice’s. In some weeks she put on just a few ounces, in others her weight leapt up.

For Alice and me, this hardly seemed a problem. I enjoyed breastfeeding and was blissfully happy. But the weighing clinic and those fortnightly interrogations did grind me down. Was I eating enough? Was baby latched on? A health visitor suggested I give formula milk: “You want to see she’s thriving,” she said. Alice was tested for a urine infection (nothing). Then we had an emergency doctor’s appointment (she was fine). But the nagging continued.

It’s difficult to describe how undermining this is. Babies don’t come with instruction manuals. From the moment they love-bomb your life, all crumpled faces and incomprehensible cries, you have an instinct to protect them. And to be told that you are failing as a mother to give them adequate food is demoralising and distressing. By week 18, I was so fed up that I decided to top her up with formula milk instead.

I didn’t realise then that I was following a well-worn path for breast-feeding women. I started to hear whispers; the charts were “flawed”, based on formula-fed babies, who tend to put on more weight than breast-fed ones (and not good weight). At first, I treated the rumours with caution, but the rumblings grew louder. One mother confessed to not taking her second baby to be weighed at all, she’d had such worry with her first.

So I looked into it, and guess what? Formula-fed babies are heavier; after the early weeks, they have higher intakes of energy compared to breast-fed babies’ lower body temperature and lower metabolic rate (on average). And the chart standards Alice was failing to meet? Based on the growth of mainly formula-fed infants.

In 2005, the World Health Organisation said it would publish new growth charts, based on the optimum growth standards of breast-fed babies. “Formula-fed infants and breast-fed infants grow differently,” said Dr Mercedes de Onis of the WHO. “The problem is that by these [current UK] charts, breast-fed babies seem to be growing poorly from as early as two to three months. But the problem is not that the baby is not growing well, it is that the standards do not reflect the growth of breast-fed infants.” And the bombshell; the WHO charts showed that British babies were significantly heavier than they should be.

So where are the WHO charts? Professor Charlotte Wright of the Royal College of Paediatrics and Child Health says they have just gone to public consultation. “The important thing is that they are introduced in a way that works and doesn’t cause confusion. People don’t realise how complicated it is.”

“Ridiculous,” counters Tam Fry of the Child Growth Foundation. “We’ve known the charts were being produced since 1993, and the dramatic way they would affect the first year of life. The work had been done.”

To Fry, this is just another example of bad child-growth policy in the UK. “One reason we have an obesity problem is because we have not properly measured our children in a sensible fashion for the last 20 years. Undoubtedly we are starting to see more children with an unhealthy weight at the end of the first year, and a lot of that is because we are feeding our children up unnecessarily.” There is also an argument that babies should be weighed less often - according to Fry, six times a year and “with accurate scales”.

This fits with Alice. In a moment of clarity, my partner and I realised that, over a month, she had put on enough weight. Rosie Dodds of the National Childbirth Trust agrees: “You don’t expect babies to grow in straight lines. They have spurts.”

So how much heavier are British babies? “The WHO reference strongly implies that we have been accepting as normal levels of weight gain that are not normal,” Wright says. “From six months, the British babies outstrip the WHO reference in weight.” A healthy one-year-old should weigh between 21lb and 26lb, not 22.5lb and 28.5lb, as the current charts suggest. At two and three years old, the recommended weights are 15 to 20 per cent too high.

Currently, only 21 per cent of women are breast-feeding at six months (many topping up with formula), although 71 per cent breast-feed to start.

At the moment, it’s not clear when the new charts will be introduced. “There’s tremendous enthusiasm behind these charts, but I hope they don’t cause panic,” Wright says. Panic? I’m furious.