anyone have any links or images on hip bone developement??


New member
I know I read somewhere about the pelvic bones needing to be developed enough to withstand the crash force from a lap belt before kids can use a booster.

and also something about how adults have a natural cage in our hip bones that help protect our internal organs.

now of course I can't find it.

I'm trying to explain why a 2 year old is NOT safe in a booster even if she is nearly 40lbs. and all the usual she has to be able to sit properly etc arguements are falling flat because Mom insists she is mature enough to sit still for extended periods of time.

so I'm looking for with a little hard data.

any help ladies please..........


Admin - CPST Instructor
Staff member


Well-known member
With that study, since it does not include ff harnessed seats, do we still think they they are safer than boosters for 4 yr olds? I know 4 and 40lb is the minimum for boosters. Do we have research that shows a child that size is safer in a ff harness than a booster?

Car-Seat.Org Facebook Group

Forum statistics

Latest member

You must read your carseat and vehicle owner’s manual and understand any relevant state laws. These are the rules you must follow to restrain your children safely. All opinions at Car-Seat.Org are those of the individual author for informational purposes only, and do not necessarily reflect any policy or position of Carseat Media LLC. Car-Seat.Org makes no representations as to accuracy, completeness, currentness, suitability, or validity of any information on this site and will not be liable for any errors, omissions, or delays in this information or any losses, injuries, or damages arising from its display or use. All information is provided on an as-is basis. If you are unsure about information provided to you, please visit a local certified technician. Before posting or using our website you must read and agree to our TERMS.

Graco is a Proud Sponsor of Car-Seat.Org! Britax is a Proud Sponsor of Car-Seat.Org! Nuna Baby is a Proud Sponsor of Car-Seat.Org!

Please  Support Car-Seat.Org  with your purchases of infant, convertible, combination and boosters seats from our premier sponsors above.
Shop travel systems, strollers and baby gear from Britax, Chicco, Clek, Combi, Evenflo, First Years, Graco, Maxi-Cosi, Nuna, Safety 1st, Diono & more! ©2001-2022 Carseat Media LLC