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Special Feature at the End 2
Watch Out for Your Child’s Accidental Ingestion!

Choking and Ingestion Prevention Scale

Scale for Preventing Accidental Ingestion/Choking

If an object fits inside either of these two circles, it can fit into a baby’s mouth.

Maximum Mouth Opening of a 3-Year-Old

Distance from the Mouth to the Back of the Throat

If something fits within these circles, a child could be at risk of swallowing or choking on it, so keep such items out of reach of babies and toddlers.

Mouth Opening of a 3-Year-Old

Around 5 months of age, infants start putting anything they can grab into their mouths. This scale shows both the maximum opening of a 3-year-old’s mouth and the distance to the back of the throat, helping to prevent choking or foreign objects from lodging there.

©️Japan Family Planning Association (JFPA)

When a three‑year‑old opens wide, the mouth’s maximum opening is about 39 mm, and the distance from the front teeth to the back of the throat is about 51 mm.

Anything within those limits can be swallowed or cause choking. Long, thin objects—or items that can bend or fold to those dimensions—are just as hazardous (see diagrams below). Check in advance and keep such items out of children’s reach, at least one metre above the floor.

Figure 1 Danger Objects that fit completely inside

It can enter the mouth and be swallowed, posing a choking risk. Examples: coins, buttons, rings, bouncy balls, magnets, nuts, candies.

Figure 2 Danger Long, thin objects

Items longer than 51 mm (such as skewers or chopsticks) cannot be swallowed whole, but with a diameter under 39 mm they can still enter the mouth and may cut or pierce it.

Figure 3 Danger Bendable objects

Even if longer than 51 mm, anything that can be rolled or folded to fit inside the checker can enter the mouth and is dangerous. Examples: cigarettes, soft rubber items, foil, springs.

Figure 4 Safe Objects that do not fit

A ball with a diameter greater than 39 mm will not fit into the checker and therefore cannot be put into the mouth.

The Choking and Ingestion Prevention Scale (JFPA) lets you test whether a child could swallow a particular item.

Available from the JFPA online shop.

(Supervision: Dr Tatsuhiro Yamanaka, Hospital Director, Ryokuen Child Clinic)