NHS officials have been criticised for allowing sales people to gain access to new mothers just hours after they have given birth.
Some parents are approached by promotion company workers while they are still on postnatal wards, a GP has warned.
Glasgow-based GP Dr Margaret McCartney questioned whether it was "desirable" for representatives from promotions company Bounty to be allowed on wards. In an editorial, published on bmj.com, Dr McCartney writes that Bounty profits by selling parents' details to other companies. But she said the hours after birth are "hardly an optimal time" to obtain consent for giving out data.
Parenting charity NCT said it was angry about the way some NHS organisations let Bounty access new mothers.
NCT chief executive Belinda Phipps said: "Within hours of giving birth, they are being asked questions - their name and address, details of life insurance - and they give them in good faith, thinking they're speaking to a hospital person. In fact it's a commercial person. The NHS is condoning a sales team collecting data from mothers in order to sell their name on to commercial interests."
Dr McCartney said commercial advertisers are also getting access to new parents through "baby bags", which contain sample products as well as a dozen flyers, which are given out by Bounty. She writes that some 2.6 million Bounty bags are given to new mothers and fathers every year. The packs have an "air of officialdom" because they also contain application forms for child benefit, she said.
The article states that HM Revenue and Customs pays £90,000 a year to Bounty to distribute the forms - even though they are available online. "So families supply their details, which can be sold on by a commercial company, which in turn is paid by the Government to supply freely available child benefit claim forms," writes Dr McCartney.
A spokesman for Bounty told the BMJ: "Over a decade ago Bounty offered to conduct a small scale pilot which satisfied HMRC that Bounty could distribute child benefit forms directly and quickly into the hands of parents as soon as they need them." He added that a poll of 4,000 parents earlier this year found that 90% said they were "satisfied" with the packs.
A spokesman for HMRC added: "We are committed to keeping our costs as low as possible. Bounty distributed 82% of all child benefit claim forms in 2012, averaging around 10p for each claim. If HMRC posted the forms individually the cost would rise to 33p for each claim making this option much cheaper and more direct than the alternative."
A Department of Health spokesman said: "Bounty packs are distributed in many areas and it is up to local NHS trusts to decide locally whether to allow them to be given to families. They can also have a say about what goes in the packs, to make sure the content is appropriate for the women and families using their maternity services."