Table 1. Length of time taken after start date for trial registration to be created for trials that were retrospectively registered.

Length of time after start date that trial was registered	Number of Articles (%)
Less than 1 month after	7 (11.5)
1 month to less than 6 months after	14 (23)
6 months to less than 12 months after	10 (16.4)
1 year to less than 5 years after	28 (45.9)
5 years or more after	2 (3.3)