New mothers and staff have criticised Pennine Acute Hospitals NHS Trust for putting up the image on the children's ward at Rochdale Infirmary.
The poster shows a child of two or three breastfeeding a doll under the headline 'It's normal' and accompanied by the caption 'Children copy their mothers, teenagers do it! Celebrities do it'.
New Muslim cartoon protests in Pakistan and IranHealth chiefs insist that the poster is designed to promote breastfeeding but critics say that the picture is 'distasteful, inappropriate and crude'.
They also claimed new mums are being made to feel like 'aliens' if they are unable to breastfeed.
Deborah Winter, aged 39, noticed the poster when she was visiting her nine-week-old grandson Scott Bowker and called for the image to be immediately withdrawn.
She said: "The picture is shocking and it isn't normal. Children copy their parents but I don't think any little girls should be breastfeeding their dolls.
"It should be up to new mums to decide whether to breastfeed and I feel that they are being pressurised instead of offered support."
Councillor Jean Ashworth, who works as a healthcare assistant at the Infirmary, said the move was the latest in a string of unpopular measures to promote breastfeeding.
"The picture is highly offensive and everyone is up in arms about it," she said: "We all know breast is best, but they are going overboard and upsetting new mums who can't breastfeed for medical reasons.
"The trust seems to be more interested in chasing awards for promoting breastfeeding rather than supporting new mums to make the best decision for them."
A spokesman for the Trust said the poster was designed for National Breastfeeding Awareness Week.
Val Finigan, the Trust's infant feeding co-ordinator, said: "We have recently launched a competition for children to paint, draw or colour any animal that they think breastfeeds. This poster and the competition is part of a larger campaign to raise awareness among children .
"There are a lot of myths still out there about breastfeeding and women still come into the hospital with misunderstandings about feeding."