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Study IDs are stored as character values to ensure that zero place holders are not dropped. The randomisation number is assigned sequentially at each site after randomisation. A decimal point is placed between the site code and randomisation number. This allows sites to monitor their own recruitment and ensures the ID can be easily converted to a numerical value if manipulations are required. The study number ensures that samples and data can be identified across studies. Site codes are based on those used in previous Australasian multicentre trials.

In multiple pregnancy, For perinatal studies,  we recommend one of the following two options to deal with unit of analysis issues: 

  1. Add a suffix where 0 is mother; infants are coded 1, 2 and 3 according to birth order in multiple pregnancy or 5 for singleton. Note that a surviving twin would be coded as 1.
  2. Assign a separate "randomisation number" to the fetuses, e.g., start mothers at 1000 and babies at 5000.


  • Mother first pregnancy in study XXXXXX.0001 to XXXXXX.2999
  • Mother second pregnancy in study XXXXXXX.9001 to XXXXXX.9999
  • Singleton fetus/neonate XXXXXX.3001 to XXXXXX.5999
  • First twin or triplet XXXXXX.6001 to XXXXXX.6999
  • Second twin or triplet XXXXXX.7001 to XXXXXX.7999
  • Third triplet XXXXXX.8001 to XXXXXX.8999

Click here for the complete list of LifePath study and site codes.