Ruth Watts, a registered health visitor who posts advice on social media, told the BBC she was not surprised that many unsafe baby products were still on the market.
“Parents are the most vulnerable consumers,” he said. “We want what’s best for our babies, we’re desperate for sleep – and if a product promises you it will help or make your baby sleep better… then it’s definitely tempting.”
When shopping for baby products, which one? Advises parents not to purchase any self-feeding aids, and that babies under one year of age do not need a pillow for sleeping at night.
It also says to never buy a baby sleeping bag that is hooded or without armholes, or with extra material or attachments, and make sure you buy the right size sleeping bag.
Watts’ advice for parents struggling to find out whether a sleep-related product is safe for babies is to check if the item is recommended by the baby sleep safety charity Lullaby Trust.
“If something sounds too good to be true, if someone is promising you a quick solution to a problem, chances are it’s too good to be true,” he said.
According to the Lullaby Trust, the safest place for a baby to sleep is on a firm, flat mattress on their back in a clear cot, with no toys inside.
Seven online marketplaces issued statements in response to the findings.
An Amazon spokesperson said it had issued a Who? has removed the highlighted products, saying it continuously monitored the products being put up for sale on its site and took quick action when alerted to potential issues.
“Parents trust Amazon because we take customer safety incredibly seriously, especially when it comes to babies and toddlers,” she said.
Alibaba said it had removed any “non-compliant products” and that it would “continue to educate sellers, and take action against those who violate our terms of use”.
AliExpress said it “takes customer safety and product compliance extremely seriously”, adding that the relevant products have been removed from the UK market and that “necessary enhancements to our existing control measures” will be made to ensure these products do not resurface.
eBay said it uses “technology, AI and expert teams” to keep unsafe items off its platform, has removed some of the flagged items and is conducting a broader investigation to remove similar items.
An Etsy spokesperson said it had contacted Which? Removed all listings marked by, and said: “Keeping our users safe is paramount.”
TikTok said the products flagged by the investigation have been removed and it has notified customers.
Onbuy said all relevant products have been removed and that it is working closely with OPSS to ensure that unsafe and non-compliant products are removed from its marketplace as quickly as possible.
A spokesperson for the Department of Business and Trade said which results? The investigation was “incredibly worrying” and any product that puts babies and children at risk should not be sold online or in stores in the UK.
“It is not enough for companies to take action when such products are flagged – they have an obligation to proactively stop unsafe products before they reach their sites,” he said.
The BBC has contacted Wish for comment.
