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

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 contrib‑
uting 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-fexion 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 swad‑
dling 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 fnal outcome data in all 80 enrollees. Percentages of cases with non-Type 1 hip at any followup 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±0.3weeks in the non-swaddling group and 8.4±0.89weeks 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.