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Quality of harness fit for normal and low birthweight infants observed among newborns in infant car seats
  1. Julie Brown1,2,
  2. John Kam Hung Sinn3,
  3. Aileen Chua3,4,
  4. Elizabeth Clare Clarke3,4
  1. 1Neuroscience Research Australia and School of Medical Science, Randwick, New South Wales, Australia
  2. 2UNSW, Sydney, New South Wales, Australia
  3. 3Sydney Medical School—Northern, University of Sydney, Sydney, New South Wales, Australia
  4. 4Kolling Institute of Medical Research, Institute of Bone and Joint Research, Saint Leonards, New South Wales, Australia
  1. Correspondence to Dr Julie Brown, Neuroscience Research Australia and School of Medical Science, NeuRA, Barker St, Randwick, NSW 2031, Australia; j.brown{at}


Introduction Child restraint fit is important for crash protection. For newborns, standards universally require a rear-facing restraint and some upper limit on size, but historically there has been no specification of a lower design limit and there is concern over whether low birthweight infants (LBW) are adequately restrained. The aim of this study was to determine the quality of harness fit for newborns of low and normal weight in a range of modern child restraints.

Methods A convenience sample of infants (1.657–4.455 kg) were recruited from the postnatal ward and special care nursery <1 week from discharge. Infants (n=84) were assessed for harness fit in rear-facing-only restraints, convertible rear/forward restraints and a subset were assessed in a restraint specifically designed to accommodate LBW infants. Measures of harness fit were based on shoulder strap, crotch strap and buckle positioning.

Results Less than 20% of infants achieved good harness fit, regardless of whether they were categorised as low (<2.5 kg) or normal weight. Rear-facing-only restraints were less likely to provide good fit than convertible restraints, in all measures of fit other than shoulder strap width. The proportions of infants achieving good fit were greater in the restraint designed for LBW infants than other restraint types.

Conclusion Poor accommodation continues to be a problem for LBW infants but is rectified in specifically designed restraints. Better specification of harness configuration for all rearward-facing restraints may be required to ensure adequate accommodation of normal birthweight infants.

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  • Funding JB and ECC were supported by National Health and Medical Research Council Fellowships. The authors gratefully acknowledge funding support of the Royal North Shore Hospital Staff Specialist Fund. Child restraint systems used in these trials were supplied by Britax, Australia, and InfaSecure Pty Ltd.

  • Competing interests None declared.

  • Ethics approval North Shore Local Health District Human Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.