A Cochrane Systematic Review that set out to assess the effectiveness and tolerability of subdermal implantable contraceptives compared to other reversible methods of contraception found that they were all good at preventing pregnancy. No one subdermal implant was found to be any more or less effective than the others in preventing unwanted pregnancies.
The most common side effect with all the implants was changes in bleeding pattern. Rates of amenorrhoea after two years use were significantly higher in women using Implanon than Norplant. Implanon was also quicker to implant and remove than Norplant, and Jadelle was quicker to remove that Norplant.
One way of judging the acceptability of a contraceptive is to see whether women are able to use them over a long period of time, there are indications of good tolerability in that over 80% of women in the studies continued to use their contraceptive implants for two or more years, says lead researcher Jo Power, who works at the Margaret Pyke Centre in London, UK.
The data also showed that women in developing countries were more likely to continue using them than were women from developed countries.
Menstrual disturbances are common however, and these side effects should be explained to women before the implant is inserted so that women can make an informed choice about their contraceptive strategy, says Power.