Observing mothers lifting their children in their own home to identify factors which might give rise to musculoskeletal disorders
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The lifting associated with childcare has been linked to musculoskeletal disorders (MSDs) in mothers (Griffin & Price, 2000; Sanders & Morse, 2005). The purpose of the current study was to investigate, for the first time through observation, the lifting of young children by mothers in the home environment to identify risk factors which might give rise to MSDs. Twenty five mothers with one or two children weighing between 9 and 15kg (n = 30) completed a self-report survey modified for the New Zealand context (The Ergonomics of Caring for Children (Sanders & Morse, 2005)). They also took part in a structured observation of lifting in the home using a checklist based on the New Zealand Manual Handling Hazard Control Record NZMHHCR (OSH & ACC, 2001). Modifications were derived from careful consultation of current literature to enable contributory factors related to the load, the mother, the environment and the task to be assessed and a rating of low, medium, or high risk to be assigned to each factor. A protocol to guide risk assessment was developed to accompany the tool. The modified observational checklist was named the OMLITH (Observing Mothers Lifting In The Home). Survey data identified the mothers as aged between 28 and 40 years, predominantly NZ European, and of average height (χ = 1.69cm) and weight (Body Mass Index = 24). The children in the sample weighed between 9 and 14.5kg and had an average age of 17months. All the mothers were either married (n=20) or living with a significant other (n=5) and their partners frequently (n=13) or always (n=12) helped with childcare. The mean time mothers spent per week on the following activities were: sleep, 6.8hrs (n=25), housework, 14.9hrs (n=25), exercise, 2.9hrs (n=22), watching television or using the home computer, 4.3hrs (n=22), hobbies, 2.2hrs (n=19), gardening or home maintenance, 2.9hrs (n=18). Thirteen of the mothers worked (3 full-time, 10 part-time) and 20 mothers used childcare services. Ratings of the physical stress associated with 50 childcare tasks showed that mothers differentiated between tasks in terms of physical stress to a significant degree (p.000), typically rating ‘Bending while carrying a child’ as almost twice as stressful as the average rating. Other categories rated significantly above the average stress rating were: ‘Use of a backpack to carry infant/child’, ‘Use of baby jogger’, ‘Carrying child on your shoulders’, ‘Standing bent over to wash child in bath or sink’, ‘Lifting child into or out of cot’, ‘Prolonged squatting or stooping while playing with child’, and ‘Placing child in car seat or removing child from car seat’. Mothers reported experiencing MSDs most commonly in the low back (n=16), and the neck, shoulder and upper back (n=8 each). Data from the 87 observations using the OMLITH showed that children were a challenging load due to their moving centre of gravity, and were often unpredictable or awkward to handle. The grip required to lift a child more often than not fell outside the National Institute for Occupational Safety and Health (NIOSH) recommendation. In 72.9% of tasks the child’s weight created a high risk level. The lifting tasks involved horizontal and vertical lift distances that presented a moderate to high risk level in 82.8% of situations. Lifting while twisting and side-bending was assigned a moderate to high risk level in 72.4% of tasks. Risk associated with working at an externally controlled pace; and handling children while seated or kneeling/crouching was also observed. The home environment presented risk associated with obstacles, a variety of floor surfaces and stairs or slopes. Mothers were also observed lifting in confined spaces. Individual factors identified as important considerations were: a mismatch between mothers’ strength and fitness and the lifting requirements, pain or injury, pregnancy, and fatigue. The structured checklist proved to be an appropriate tool to identify the contributory risk factors present when mothers lift in the home and to make an assessment of the level of risk. Results suggest a notable number of risk factors which might give rise to MSDs are present when mothers lift their children at home. The author concludes that further research is warranted to quantify risks, to identify prevention strategies for MSDs in this population, and to guide health providers with regard to treatment and rehabilitation of mothers with MSDs.