The pregnancy rate associated with use of an implant is very low < 1 in 1000 over 3 years. Most pregnancies
have occurred when the client was already pregnant prior to insertion of the implant or had not observed
contraceptive cover after initial fitting.
No increased risk of pregnancy has been demonstrated in women weighing up to 149kg. However because of
the inverse relationship between weight and serum etonogestrel levels a reduction in the duration of
contraceptive efficacy cannot be completely excluded. Women using the contraceptive implant should be
informed that earlier replacement can be considered in obese women (but there is no direct evidence to support earlier replacement).