This is a double blind, placebo controlled, randomised study with an additional randomised non-blinded arm. Two hundred women between the ages of 18-45 years, who are Implanon users with prolonged or frequent breakthrough bleeding (WHO definition) will be recruited and randomised into 4 equal-sized treatment groups of 50 women assigned to Marvelon 7 days or 21 days, NuvaRing 21 days or placebo. Recruited subjects will maintain a daily menstrual diary chart for a minimum of 90 days prior to randomisation, and will be enrolled into the treatment phase provided that they have met one of the World Health Organization criteria for prolonged or frequent bleeding (in the 90 day reference period one episode of bleeding and/or spotting lasting > 10 days, or more than 4 bleeding/spotting episodes). Randomisation will be performed by computer generation of a random number table in blocks of ten, with equal numbers in each of the four groups. The medications will be packed in sequentially numbered and sealed opaque envelopes (independent of the investigators).