The NHS began to incentivise mothers across the country last year, and trials which offered women up to £200 in shopping vouchers if they breastfed their children found that half of those offered the initiative signed up for it, and two thirds breastfed for six weeks.
More than 4,000 women will now be offered the scheme, which pays out £120 in vouchers for those who breastfeed for six weeks, rising to £200 for those who reach six months.
Health experts said the scheme aims to tackle 'stubbornly low' rates of breastfeeding in parts of the UK.
Under the scheme, mums will be given £120 worth of vouchers from Argos, Debenhams, Poundstretcher and supermarkets Tesco, Asda and Morrisons, if they sign forms declaring that they have breastfed their child for six weeks, with a further £80 at six months.
Mothers taking part said they'd spent the vouchers on groceries as well as nappies, baby clothes and toys.
Mums in three areas of Derbyshire and South Yorkshire where breastfeeding rates were low - between 21 per cent and 29 per cent - were offered vouchers of up to £200.
Of the 108 eligible for the trial scheme, 37 earned vouchers for breastfeeding for six to eight weeks.
However, critics, including leading doctors, said the scheme amounts to 'bribery'.
Dr Colin Michie, from the Royal College of Paediatrics and Child Health, said: "You're asking for a payback from some mums who can't necessarily give it.
"Not all mothers can breastfeed for a range of reasons - so it's just not fair. It is essentially a bribe if you're offering money for breastfeeding.
"This pilot scheme has been a success - but it would be nice if we could incentivise mums to breastfeed without paying them."
However, mum Vanessa Purdy, 31, who is still breastfeeding her eight-month-old, James, told the BBC: "The vouchers lure you into the scheme and breastfeeding. But the confidence you gain, and the friends you make through the scheme, is unbelievable.
"It's that support network, not the money, that spurs you on to continue. It broke down the barriers and got everyone talking about the vouchers.
"It made breastfeeding feel normal and natural to me. And the money was useful for daily shopping and a few treats. I even tried tuna steak for the first time."
Principal investigator Dr Clare Relton, from the University of Sheffield's School of Health and Related Research, said: "For several decades now the majority of babies in the UK have not been getting enough breast milk, and despite many efforts, this situation has not improved.
"Now we need to conduct the full trial to find out if offering vouchers for breastfeeding can significantly increase our stubbornly low breastfeeding rates and be a cost effective use of UK public funds.
"Last year, there was a lot of controversy about the scheme and we didn't know if it would be acceptable, so we have been delighted to see how enthusiastic local mothers and healthcare professionals have been."
Cathy Warwick, chief executive of the Royal College of Midwives (RCM) said: "The RCM is interested in these initial findings and it is clearly important given the serious need to improve breastfeeding rates that these are explored further."
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