Parents of small children need to be aware of the dangers of carrying them on bicycles without child seats.

Thirty medical institutions across the country treated 40 cases over a 5-year period to July, in which babies, strapped to their mother’s backs, suffered injuries when their parents had bicycle accidents.

Wow, a whole 40 cases over 5 years? Considering the thousands of children that are carried in this manner, I don't see a problem. In fact, carrying the child on your back is probably safer, since you can move your body to shield/brake the fall. A kid strapped in a seat means the rider has to manange the bike and his/her own fall. An added point is the attached weight of the child has a tendency to unbalance the bike.

The report doesn't say whether only thirty hospitals in the entire country had cases or whether only thirty hospitals were surveyed.

Anyway, the issue here is a child seat on a bike is designed and tested to carry kids on a bike (doh!). A strap style baby carrier is not designed and tested to carry a baby on a bike. Some baby carriers are loose and many hold the baby by gravity, which won't work when the parent is horizontal after a cycling accident. This mightn't be a problem with Ergo baby style rugged carriers, but only the minority have them. Most people have cheaper ones. A bike child seat will also put the baby lower than a sling, making the bike more stable and lowering the distance of any fall. People who go cycle touring put their stuff in paniers (low center of gravity). They do not carry huge rucksacks.

It is even more dangerous when they put them in the basket not strapped in or without a helmet.

Bicycle safety in Japan is a fraught topic. not just kids on or being carried on bicycles. riding on pavement, riding with umbrella, using keitai, wrong way in the road etc etc. they all have a death wish.

Certainly much safer than transporting a child in car. Much respect to these Moms.