14 DAY TRIAL // Pill, patch or implant? Which way will women choose to overrun their body with progesterone, the anti-pregnancy hormone? The hormonal implants are barely employed in developed countries and only a bit more popular in developing countries, but a new review shows that implantable contraceptives are highly effective.
Three kinds of implants were analyzed: Implanon, Jadelle and Norplant. The meta-analysis was made on 9 researches that lasted 2-5 years, and encountered a total of five pregnancies among the 2,776 subjects. "No one implant was found to be any more or less effective," said co-author Rebecca French, a senior research fellow with the Margaret Pyke Centre at University College London.
"These numbers are not surprising. Surveys conducted in the US, which asked women about pregnancies that occurred while they were using birth control, suggest that five in 10,000 women who use implants will become pregnant during a yearlong period. By contrast, U.S. studies suggest that about three in 1,000 women who correctly use the birth control pill for a year will get pregnant; the number is estimated to be eight in 1,000 among women who miss some pills. Implantable contraceptives are very effective methods for preventing unplanned pregnancy," said French.
The implants are inserted under the skin of the upper arm, releasing the progesterone into the bloodstream. "This thickens the mucous in the cervix, which makes it difficult for sperm to travel through the cervix to reach an egg. Implants also work by making the lining of the womb thinner, making it less likely to accept a fertilized egg," said French.
The first contraceptive implants have been developed in the 1980s, and by 2003, about 11 million women worldwide were using them. The 9 researches compared one type of contraceptive implant to another; but none compared implants to other forms of contraception. 8 studies (made on 1,578 subjects) compared Implanon to Norplant; while the nineth, made on 1,198 women compared Jadelle to Norplant. "There were no pregnancies in the studies that compared Norplant to Implanon. In the one other study comparing Norplant and Jadelle, there were three pregnancies among Jadelle users and two among Norplant users," said French.
Only Implanon is currently available in the US. Irregular vaginal bleeding was the main side effect of the implants, but over 80 % of them were still using their implant two years after. "Women in developed countries were much more likely to say that they discontinued using implants because of changes to their menstrual cycle. Few women in developing countries gave this as a reason for discontinuation." said French.
Implanon and Jadelle is much easier to implant and remove than Norplant. "The makers of Norplant decided to stop marketing it in the U.S. in 2002 after multiple complaints about side effects. That negative publicity might explain why American women have not embraced contraceptive implants. Women now have a variety of options for long-acting birth control, including Depo-Provera (given via injection) and contraceptive patches," said Andrew Kaunitz, professor and assistant chairman at the University of Florida's Department of Obstetrics and Gynecology. "The implants are also expensive, costing several hundred dollars each plus the cost of implantation," Kaunitz said.
Birth control pill are much less expensive. "Though initial costs are high for implants, in the long term the devices are cost-effective because they reduce costs associated with unplanned pregnancy," said French.
"Implants might become more popular if their manufacturers advertise them. After all, they are actually more effective at preventing pregnancy than surgical sterilization, and the implants are reversible - women can become pregnant again once a clinician removes the implant." said Kaunitz.