Baby Walker Related Injuries
Baby Walkers: An Attempt To Assess Injury Risk Compared With Some Other Nursery Products
Disclaimer
This is a brief analysis written in response to a specific question for one of NISU's clients.
It uses available data and should not be viewed as a detailed piece of research. NISU releases this
information in the interest of ensuring that work done for one client can inform others. Copies are
only available on direct request to NISU and the paper must not be quoted or cited without written
permission of NISU.
NISU was asked to address the question of whether baby walkers present a higher level of risk
than other nursery products..
The data set available for undertaking this analysis in Australia is the ISIS system. Between
40 to 50 hospital emergency rooms throughout Australia have provided data to NISU over the period
June 1986 to June 1993. Hospitals cooperating with the ISIS system form a convenience sample and
therefore will not necessarily be representative of all injured persons who present to hospitals in
Australia. For these reasons, ISIS data should be interpreted with care, particularly in
considerations about the absolute frequency of injury occurrence, and in drawing regional
comparisons. The data are generally better suited to characterising the circumstances in which
injury occurs, the types of injury associated with particular causal factors, and the relative
importance of particular classes of injury.
ISIS data was used to undertake a comparison of the risk of injuries related to baby walkers
compared to other nursery products. A total of 12,360 injuries to children aged from 6 to 12 months
were extracted. Of these 631 involved baby walkers. A review of product related factors showed this
to be the highest single product category for this age group. In order to provide a comparison, 7
other nursery products were selected. These consisted of the five next most frequent product
categories in the injury data base: high chairs, strollers, changing tables, prams and cots, and
two products used for 'child minding': baby exercisers and playpens.
The ISIS system is a sentinel collection. It is not possible to calculate actual injury rates
as the population served by contributing hospitals is unknown. The population served is however
constant across products (eg baby walkers, cots, prams etc.). The number of injuries for each
product can be viewed as an unbiased estimate and the ratio of these counts (say for baby walkers
and cots) can be viewed as an unbiased estimate of the relative frequency of injury. The number of
cases in the age group under study is large and therefore sampling errors would be small. The data
are appropriate for assessing the relative hazardousness of products.
Results
Table 1 shows the number of injuries and admissions from each product category and the relative
frequency index for each product when compared with baby walkers. The index represents the numbers
of injuries involving that product for each 100 injuries involving baby walkers.
All of the products in the comparison show a much lower frequency of injuries for the target
age group than baby walkers. The relative severity of baby walker injuries is reflected by the fact
that the relative frequency index for admissions related to comparison products, is consistently
lower than for all injuries. One exception is the case of baby exercisers where there is a low rate
of injury but the proportion of those cases admitted is relatively high.
Table 1
Numbers Of Injuries And Admissions And Relative Frequency Index
(RFI) Of Baby Walker Related Injuries To Other Nursery Products
Children Aged 6 To 12 Months
ALL INJURIES ADMISSIONS
RFI of RFI of
N injury N admission
Baby Walker 631 100.0 110 100.0
High Chair 285 45.2 42 38.2
Strollers 218 34.5 29 26.4
Changing Tables 195 30.9 27 24.5
Prams 185 29.3 23 20.9
Cots 127 20.1 12 10.9
Baby exercisers 30 4.8 10 9.1
Playpens 12 1.9 1 0.9
Total 1683 254
Baby walkers are generally used between the age when children crawl and when they can walk
independently. Table 2 shows how the relative frequency index changes over this period. Overall the
baby walker shows a pattern of higher risk although high chairs, strollers and cots show higher
index scores for children 12 months old. This possibly reflects lower use of baby walkers as many
children are walking by this time.
Table 2
Relative Frequency Index of Baby Walker Injuries And Admissions
To Those Related To Other Nursery Products By Age In Months
Age in months
6 7 8 9 10 11 12 6 to 12
ALL INJURIES
Baby Walker 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
High Chair 37.5 23.7 21.5 36.4 55.7 120.0 200.0 45.2
Strollers 40.6 27.1 13.3 27.3 27.3 90.0 161.9 34.5
Changing Tables 56.3 32.2 28.5 19.7 28.4 22.0 66.7 30.9
Prams 37.5 29.7 19.0 23.5 28.4 44.0 85.7 29.3
Cots 15.6 11.0 14.6 12.1 18.2 48.0 119.0 20.1
Baby exercisers 17.2 10.2 0.6 2.3 0.0 2.0 9.5 4.8
Playpens 0.0 0.8 1.3 3.0 2.3 4.0 4.8 1.9
ADMISSIONS
Baby Walker 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
High Chair 25.0 15.6 15.4 38.5 57.9 100.0 300.0 38.2
Strollers 25.0 9.4 15.4 23.1 15.8 180.0 133.3 26.4
Changing Tables 25.0 15.6 26.9 30.8 26.3 40.0 33.3 24.5
Prams 16.7 9.4 11.5 23.1 21.1 80.0 133.3 20.9
Cots 8.3 6.3 19.2 7.7 5.3 0.0 66.7 10.9
Baby exercisers 33.3 9.4 0.0 0.0 0.0 20.0 66.7 9.1
Playpens 0.0 0.0 0.0 0.0 5.3 0.0 0.0 0.9
The estimates above do not take into account the relative frequency of use of the products.
There are no detailed data on the length of time to which children of this age are exposed to each
product. Ownership by households where there was a child under the age of one year was estimated
for Melbourne by the Australian Bureau of Statistics for three products, baby walkers, prams and
strollers and high chairs1. Baby walkers were further assessed as being in use or not in
use.
If it is assumed that ABS findings for Melbourne apply to the population from which the ISIS
cases came, then it is possible to derive an exposure adjusted relative frequency index. Index
scores have been adjusted by the ratio of baby walker ownership to ownership of the other products.
(Table 3) The ownership of high chairs and prams and strollers was higher than for baby walkers,
therefore the index score has decreased. When allowance is made for the proportion of baby walkers
not in use, the index decreases further. This is based on the assumption that all prams / strollers
and high chairs were in use and only 20% of households had baby walkers in use. (Based on ABS
data). This indicates that when exposure is considered baby walkers are still far more likely than
comparison products to be involved in injury events.
Table 3
Relative Frequency Index Of Baby Walker Injuries Adjusted For
Ownership And Use Of Both Products
Unadjusted Adjusted for Adjusted for
ownership ownership
and use
Pram or 63.9 19.8 13.2
stroller
High chair 45.2 16.7 11.2
Table 4 considers injuries resulting in admission. Once again,
the low index for comparison products indicates a far higher risk
for baby walkers even after taking into account ownership and
use.
Table 4
Relative Frequency Index Of Baby Walker Admissions Adjusted
For Ownership And Use Of Both Products
Unadjusted Adjusted for Adjusted for
ownership ownership
and use
Pram or 47.3 14.6 9.7
stroller
High chair 38.2 14.1 9.4
It is possible that the high relative frequency of baby walker injuries may be due to the number
of hours of use of baby walkers rather than a high risk per hour of use. If it is assumed that each
of the product types has the same risk per hour of use as baby walkers then the number of hours use
required to produce an equal number of injuries and admissions as baby walkers can be estimated for
three nursery products. The results are shown in Table 5. The results show that even low hours per
day use of baby walkers would require almost constant use of the other products examined to result
in the same number of injuries. This suggests that an assumption of equal risk per hour of use is
unlikely to be correct.
Table 5
Estimated Number Of Hours Of Exposure To Other Products To
Produce Injuries And Admisssion Numbers Equivalent To One Hour's
Use Of A Baby Walker.
NO. OF HOURS
INJURIES
Pram or stroller 8
High chair 9
Cot 25
ADMISSIONS
Pram or stroller 10
High chair 11
Cot 46
Note: Calculations are based on Melbourne estimates of baby
walker use. 1
Discussion.
Comparative risk.
Baby walkers show a much higher level of risk than other nursery products. It should be noted
that both prams / strollers and high chairs have design and safety harness problems which require
attention and which, if rectified, would result in an increase in the measured relative risk of
baby walkers. The highest relative frequencies of injury and admission associated with baby walkers
are in the age groups seven to nine months. These are the main age groups targeted for baby walker
sales. In the absence of detailed exposure information it is impossible to judge whether this is
due to increased exposure at these ages. While detailed exposure data is lacking, the estimates of
relative frequency show such a marked excess for baby walkers that it is unlikely that differential
exposure would account the imbalance. In any case, the absolute and relative numbers of injuries,
regardless of exposure, justify some preventive action.
Design difficulties.
Baby walkers are targeted at children with very limited abilities. Among those children aged 6
to 12 months injured in a baby walker, in excess of 50% of injuries involved stairs or steps. This
is what might be expected given the abilities of the child at that age. The task of perceiving a
change in level, assessing the risk and responding appropriately is almost certainly beyond the
capability of such young children 2.
Society already has recognised the need to prevent access to products which are not within the
capabilities of the user. For example, driver's licences are not issued until sixteen years of age
in any state and there is a move to introduce a uniform 18 year old limit. Small parts in toys are
a recognised hazard and labelling warns parents not to provide access to such toys among children
under three years of age. The paradox of the baby walker is that it specifically targets a product
at an age group that does not have the developmental capabilities to use it safely and by the time
perception improves to the point where children can safely use a baby walker, they no longer need
it. It can therefore be argued that a case could be made that injuries are caused by the product in
that its design fails to adequately take into account the developmental abilities of the targeted
user.
A product which does not take into account the developmental abilities of the prime user and
which moves at speeds of up to 1 metres per second 3, which increases the kinetic energy
potential of any impact by raising the heaviest part of the child, the head, above standing height
and allows it to accelerate to high speeds, carries risks which cannot be realistically managed by
supervision. Changes to the home environment to stop access to stairs and steps and other dangerous
situations would need to be extensive in many homes and would cause difficulties for other
residents and would be likely to fail as they would require repetitive human action to maintain the
protective environment.
Conclusion
Baby walkers carry a risk of injury which is considerably elevated compared to other nursery
products. Baby walkers fail to take into account the developmental abilities of the prime user in a
way which directly contributes to injury. The design of the baby walker can therefore be considered
faulty.
References
Australian Bureau of Statistics, Safety in the Home Melbourne
ABS Melbourne 1992 Tables 18, 24,28.
Valsiner J, 1985 Theoretical issues of child development and
the problem of accident prevention. In Garling T and Valsiner
J, (eds) Children within environments (pp13-36) New York:
Plenum
Federal Bureau of Consumer Affairs Discussion paper Trade
Practices Act 1974: Division 1A of part V: Consumer Product safety:
Need for mandatory action: Baby Walkers Canberra FBCA 1993.
pg 9
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