If a woman decides not to breastfeed her baby it is her choice and must be respected, midwives are being told.
The Royal College of Midwives' new position statement makes it explicitly clear that women should be supported if, after being given advice, information and support, they opt to bottle feed using formula milk.
Although breast is best, often some women struggle to start or sustain breastfeeding, says the RCM.
Informed choice must be promoted.
The National Childbirth Trust says women can experience unacceptable levels of pressure however they feed their babies – from family and friends, as well as from people they hardly know.
Mothers who breastfeed their babies often feel pressurised and constrained about whether, where, how often, and how long they breastfeed. Similarly, mothers who use formula milk often feel judged or guilty too, particularly – but not only – if they planned to breastfeed.
Researchers at Liverpool University studied the experiences of more than 1,600 new mums in 2016. Among the 890 who did formula feeding, 67% reported feeling guilty, 68% felt stigmatised and 76% felt the need to defend their feeding choice.
Similar emotions were less common but still present among the breastfeeding mums, particularly for those who supplemented breastfeeding with formula.
Investigator Dr Victoria Fallon, from the university's school of psychology, said: "We looked at a range of emotions and found that women who started exclusively breastfeeding but then stopped were most likely to feel guilty, while those who bottle-fed from birth often felt stigma."
Nicola Kay had a very difficult birth, but wanted to breastfeed her son Ethan. It took several days for her milk came through. "He was crying and sleeping a lot because he wasn't getting the food he needed," she said.
"Most of the midwives were insistent that I continue to breastfeed, but then in the middle of the night he wouldn't stop crying, and I couldn't feed him.
"A midwife came in and asked me if I wanted to give him some formula. I did and I felt a mixture of guilt and relief that he was eating."
The 32-year-old did begin expressing milk, but she had to feed her son from a bottle rather than a breast.
"I was given loads of advice, but in the end it just wasn't happening and I thought the best thing to do was feed with formula."
The scientist from North Wales said she did not receive the same support when she switched to formula, and added: "It felt like I'd been abandoned.
"No-one said I'd made the wrong choice, but it was hinted that I made the wrong choice."
Tabby, 33 and from North London, wanted to breastfeed exclusively but was worried that her son, Arthur, was not putting on enough weight.
"I tried for three weeks. It was incredibly stressful. You feel like you're not providing for your child. I felt like I was failing him."
Tabby spoke with her midwife who organised for a breastfeeding advisor to visit her and Arthur at home.
"That gave me the confidence to know what I had been doing was right. I was feeding properly, but Arthur still wasn't putting on enough weight. We ended up putting him on some formula as well as breast milk. They were concerned that he might have dairy intolerance so I also stopped drinking milk and eating any dairy.
"I'm so glad the midwife acted quickly. By giving some formula it helped me continue to breastfeed Arthur."
Keilly, from London, says she was given conflicting advice about how to feed her baby girl, Amelie.
"One health visitor told me I should top Amelie up with formula because she was underweight, but another one said I absolutely should not put her on a bottle. It was so confusing.
"I think it's hard for first-time mums to know what to do for the best. In the end, we gave Amelie one bottle a day and did the rest with breastfeeding. With hindsight, we probably didn't need to and could have stuck with exclusive breastfeeding instead, but it worked for us as a family."
Breast, bottle or both
The UK has one of the lowest rates of breastfeeding in Europe.
Although most new mothers try it initially, less than half are still exclusively breastfeeding when their baby is six weeks old. This drops to about 1% at six months, figures suggest.
Experts recommend, whenever possible, babies should be exclusively breastfed for the first six months of their life, and breastfeeding should continue for up to two years or beyond alongside introducing solid foods.
But, ultimately, it should be the woman's choice, says the RCM.
Chief Executive Gill Walton said: "The RCM believes that women should be at the centre of their own care and as with other areas of maternity care, midwives and maternity support workers should promote informed choice.
"If, after being given appropriate information, advice and support on breastfeeding, a woman chooses not to do so, or to give formula as well as breastfeeding, her choice must be respected.
"We recognise that some women cannot or do not wish to breastfeed and rely on formula milk. They must be given all the advice and support they need on safe preparation of bottles and responsive feeding to develop a close and loving bond with their baby."
Dr Fallon says the advice is a step in the right direction, but she is concerned that current breastfeeding promotional strategies are not "mum-friendly" enough and can foster negative emotional experiences.
"We can't dispute the health benefits of breastfeeding, but in the UK we have one of the world's worst breastfeeding rates even though lots of women do say they want to breastfeed.
"Breastfeeding promotion needs to be accompanied by practical and emotional support."
The National Childbirth Trust runs a helpline offering advice on infant feeding and other pregnancy and parenting issues.