Sales reps who sell to new mothers on NHS maternity wards in the UK should be banned, parenting forum Mumsnet says.
Staff from the promotions firm Bounty are allowed access to mothers who have recently given birth in NHS hospitals to offer free samples and collect personal details.
Some 82% of mothers who responded to a Mumsnet questionnaire said sales reps should not be allowed on wards.
A Bounty spokeswoman said complaints about its activities were rare.
Of more than 1,000 mothers who completed the online survey, over half (56%) felt the Bounty rep had invaded their privacy.
The survey was open to mothers who had given birth in an NHS hospital in the past year. Some 60% said they were not specifically told that their personal details would be passed on to other companies.
Over half (55%) said the rep came at an inconvenient time for them and their baby, while 48% said they were not told that giving their details was voluntary.
Some 53% rated the post-natal Bounty pack as poor with not much of use inside, while almost a third (29%) felt pressurised by the firm's staff into having their baby's photograph taken.
Some 17% said the Bounty rep implied they would only be able to claim Child Benefit if they filled in the company's forms.
Justine Roberts of Mumsnet said: "Our users believe it's time for the government to clamp down on Bounty's harassment tactics to obtain data from new mothers.
"There is a time and a place for direct sales and it's not on postnatal wards, hours after women have given birth. Women rightly expect hospital wards to be a safe place and targeting new mothers at their most vulnerable is simply not on."
Mumsnet's move follows similar calls from the National Childbirth Trust and some doctors. Activists have also launched an online petition asking the health minister, Dr Dan Poulter, to exclude "commercial parenting club reps" from maternity units.
Bounty updated its code of conduct a year ago in response to criticism that its reps could be intrusive and insensitive at a time when mothers were particularly vulnerable.
A statement from the company says it would welcome dialogue with Mumsnet and is saddened to hear of any instances where it falls short "of the high standards that mums demand of us and we demand of ourselves".
The firm says it has an independently run research panel of 37,000 participants that is "more representative of UK mums" - and says data from the panel suggests the vast majority are happy with its quality of service and staff.
"Complaints are rare for us and the most common complaint we receive is when mums miss seeing the Bounty lady," said the company.
Bounty says 96% of new mothers sign up to its service which offers free samples and advice to some 2.5m members.
A Department of Health spokesman said "It is up to local NHS hospitals to decide locally whether to allow Bounty representatives on to their maternity wards. They also have a say about which mums the representatives are allowed to visit and when.
"We do not hold any central contracts with Bounty or have any influence over the conduct of their sales representatives. But as with all hospital visitors, we would expect them to respect the privacy of all women and their families."