Table 1

Summary of the reasons for implant failure during postmarketing use of Implanon (2005–2009) and Nexplanon (2012–2016)

Assessment categoryImplanon*Nexplanon*χ2
Missing implant†68 (30%)52 (22%)p=0.08
Drug interaction‡22 (10%)9 (4%)p=0.02
True method failure§122 (53%)148 (63%)p=0.04
Wrong timing of insertion17 (7%)18 (8%)p=1.00
Other¶0 (0%)7 (3%)p=0.02**
Total 229 234  

  • *Numbers of cases reported (percentages of total for each group).

  • †A missing implant was defined as one not present in the body at the time pregnancy was diagnosed.

  • ‡Includes with antiepileptic, antiretroviral and antitubercular drugs and St John’s wort.

  • §This category was assigned if no other reason for pregnancy could be determined.

  • ¶Included device expelled, damaged/broken device and placebo device inserted.

  • **Fisher’s exact test.