Three unintended pregnancies were reported in women using levonorgestrel implants while on an efavirenz based regimen.

Late breaker 86 reported that in only one woman was the level of efavirenz below the recommended therapeutic level.

The authors suggest that, if a depot gestagenic contraceptive is used, women should be informed of the small risk of pregnancy and advised that nevirapine or ritonavir boosted lopinavir may be safer choices in this setting.