Contraceptive implant (rod)P-stav

The contraceptive implant is a thin, flexible rod, 4 cm long and 2 mm in diameter, containing only the hormone progestogen. It prevents ovulation and is the safest form of contraception.  

Bleeding when using the contraceptive implant
When using the contraceptive implant, your menstruation will change. Some will no longer have menstrual bleeding, while others have a normal cycle, and a few will experience irregular bleeding. The bleeding may be a nuisance, but it is not dangerous.

Source: Sex og samfunn