At least 116 accidents in which babies were injured after falling out of baby carriers have occurred since 2009, the Tokyo metropolitan government has said.
There were a number of such serious injuries as skull fractures and traumatic subarachnoid homorrhage, the government's findings found.
Some models of baby carriers manufactured abroad have become popular in recent years, but apparently do not suit the average size of Japanese babies.
The Tokyo government established a council composed of experts and business representatives to begin drawing up safety guidelines. The council will come up with proposals within this year and present them to the central government.
This year, the Tokyo government received a report from the National Center for Child Health and Development saying that there was a series of accidents that children fell from baby carriers.
Then the Tokyo government launched its own investigation as to the number of treatments made at the centre and the number of ambulance mobilized to handle such cases in Tokyo between January 2009 to this May.
Only those accidents reported in Tokyo were covered in the investigation. Therefore, the number of such accidents for the whole of Japan is bigger.
According to the Tokyo government, the problems have involved baby slings as well as carriers that feature a belt that is secured around the adult's waist.
Forty-three of the 116 cases were accidents that occurred while the baby was being carried on the mother's back, while 73 cases occurred when the baby was positioned in front.
Twenty-six cases resulted in serious injuries, with 15 of them involving babies less than 4 months old.
In March 2013, when a mother tried to take her wallet out of her bag and leaned forward, her 4-month-old baby fell out. The child hit the ground headfirst and suffered traumatic subarachnoid hemorrhage.
In April 2012, a 2-month-old baby slipped out through a gap between the mother's body and a frontal baby carrier.
The fall resulted in bleeding in the inner right ear.
When examining how the accidents occurred, 57 cases were "at the time of putting on or taking off the carrier," 16 cases were "when the mother leaned forward" and another 16 cases were "when a tie or a fastener came loose."
According to the Tokyo government, somewhere in the range of 800,000 to 1 million baby carriers are sold in Japan every year.
The Consumer Product Safety Association has called on domestic makers to double up on fasteners while advising mothers not to position babies less 4 months old vertically in the carriers.
But in recent years, foreign-made baby carriers have been popular because of their usability and design, with half of the products sold on the domestic market are imported.
Some foreign-made baby carriers are poorly suited to Japanese figures, and in case of imports, there are no instructions written in Japanese.