Expectant mothers have accused Caffe Nero of implementing a 10p-a-cup 'pregnancy tax' on ­decaffeinated coffee.

They say that they have no option but to pay the surcharge on decaffeinated beverages because caffiene is linked to health issues and miscarriages.

Pregnant mothers are warned that surplus amounts of caffeine can lead to low birth weight as well as making babies vulnerable to health problems in later life.

Expectant mums have accused Caffe Nero of discriminating against them by charging more for decaffeinated coffees

Caffe Nero argues that it has to charge more for decaffeinated beverages because the process of taking the caffeine out is more expensive

Campaigners say that other high street chains, such as Starbucks, Costa and Pret A Manger charge the same amount for for ordinary coffees as they do for decaffeinated drinks.

Siobhan Freegard, founder of ­parenting website Channel Mum, told The Sun on Friday: 'Pregnant mums don't have a choice.

'They drink decaf to ensure their baby's safety, so charging a whopping 10p a cup more for it is indeed a 'pregnancy tax'.

'It seems like a sly way to make extra money at a time when mums-to-be need to be saving, not spending over the odds.'

Manufacturers point out that decaffeinated coffee is pricier because it costs more to remove the caffeine.

A Caffè Nero spokesman said: 'Our decaffeinated coffee costs us more to produce as we ship our beans to a specialist facility in Germany for careful decaffeination using no chemicals.

'For this we charge customers a modest 10 pence supplement.'