Traditional Mongolian swaddling and developmental dysplasia of the hip: a randomized controlled trial

Abstract Background Mongolian traditional swaddling of infants, where arms and legs are extended with a tight wrapping and hips are in adduction position, may lead to abnormal maturation and formation of the hip joint; and is a contributing factor for developmental dysplasia of the hip (DDH). This hypothesis was tested in this randomized controlled trial. Methods Eighty newborns with one or two hips at risk of worsening to DDH (Graf Type 2a; physiologically immature hips) at birth were randomized into 2 groups at a tertiary hospital in Ulaanbaatar. The “swaddling” group (n = 40) was swaddled in the common traditional Mongolian method for a month while the “non-swaddling” group (n = 40) was instructed not to swaddle at all. All enrollees were followed up on monthly basis by hip ultrasound and treated with an abduction-flexion splint if necessary. The groups were compared on the rate of Graf’s “non-Type 1” hips at follow-up controls as the primary outcome. Secondary outcomes were rate of DDH and time to discharge (Graf Type 1; healthy hips). In addition, correlation between the primary outcome and swaddling length in days and frequency of swaddling in hours per day were calculated. Results Recruitment continued from September 2019 to March 2020 and follow-up data were completed in June 2020. We collected final outcome data in all 80 enrollees. Percentages of cases with non-Type 1 hip at any follow-up examination were 7.5% (3/40) in the non-swaddling group and 40% (16/40) in the swaddling group (p = 0.001). There was no DDH case in the non-swaddling group while there were 8 cases of DDH in the swaddling group. The mean time to discharge was 5.1 ± 0.3 weeks in the non-swaddling group and 8.4 ± 0.89 weeks in the swaddling group (p = 0.001). There is a correlation between the primary outcome and the swaddling frequency in hours per day (r = 0.81) and swaddling length in days (r = 0.43). Conclusions Mongolian traditional swaddling where legs are extended and hips are in extension and adduction position increases the risk for DDH. Trial registration Retrospectively registered, ISRCTN11228572