The first oral contraceptive pill was approved by the FDA in the 1960s. “The pill” was the first reliable form of medical technology that was able to combat the social issues of family planning and population control, and it quickly rose to become the preferred method of birth control for women in America. While it is still the preferred method of birth control, with 15.6% of women aged 15-44 using oral contraception, long-lasting reversible contraceptives (LLRCs) have been growing in popularity since the turn of the century. The two most popular LLRCs are intrauterine devices (IUDs), which are used by 7.2% of US women, and the contraceptive implant, which is used by 1.6% of women.
So why the sudden rise in popularity? Here are some reasons:
- User error is out of the question – women don’t need to remember to take a pill at the same time every day
- Improvements in technology have made these devices safer and longer-lasting
- Depending on the device, LLRCs remain effective for between 3 and 12 years
- LLRCs are over 99% effective – nearly as effective as sterilization
- Women can experience lighter or even no periods
The purpose of this blog will be to explore how the biomaterials of IUDs and implants contribute to the effectiveness and long-lasting properties of these devices. In addition, potential areas for further innovation will be explored, including ways these devices can be engineered to last for longer periods of time. Another area of exploration is the possibility of these devices being engineered to be biodegradable, an area of research particularly relevant for implants. This could prevent the need for a second procedure to remove the device.
So with that, let’s take a look at an overview of how these devices work.
The Hormonal Intrauterine Device (IUD)
Hormonal IUDs are small, flexible, T-shaped devices inserted into the uterus that are designed to prevent pregnancy through the continuous, slow release of the hormone levonorgestrel. Levonorgestrel prevents pregnancy by inhibiting sperm survival and motility, thickening the cervical mucus, and interfering with endometrial maturation. There are currently four FDA approved hormonal IUDs with varying sizes and amounts of levonorgestrel released, but all are equally as effective. Depending on the type, a hormonal IUD can last between 3 and 6 years.
Composition:
- Low density polyethylene frame
- High density polyethylene removal threads
- Hormone reservoir, made up of polydimethylsiloxane, that slowly releases levonorgestrel over time
- Contains barium sulfate to make it radio-opaque (able to be detected on an x-ray)
The Copper IUD
The copper IUD is also a small, flexible, T-shaped device inserted into the uterus. The copper IUD does not contain hormones. Instead, it releases copper ions, which impede the mobility of sperm and create a toxic environment. It also causes a local inflammatory response that leads to phagocytosis of sperm, contributing to prevention of pregnancy. Unlike hormonal IUDs, the copper IUD can last for 10-12 years. In addition, there is currently only one FDA approved copper IUD, ParaGard.
Composition:
- Low density polyethylene frame
- High density polyethylene removal threads
- Body and transverse arms wound with copper wire
- Barium sulfate throughout
Contraceptive Implant
The implant is a small, flexible rod that is inserted under the skin in the upper arm through a minor surgical procedure. The implant continuously releases a low amount of etonogestrel, a type of progestin. Etonogestrel prevents pregnancy by preventing ovulation, interfering with endometrial maturation, and thickening vaginal fluid to immobilize sperm. Like IUDs, implants are over 99% effective, but the one downside is that the hormones are released throughout the body rather than locally. The implant also has to be removed through a minor surgical procedure after 3 years, as it is not biodegradable. There is currently only one contraceptive implant that is approved by the FDA, Nexplanon.
Composition:
- Non-biodegradableethylene vinylacetate copolymer membrane
- Barium sulfite to make it radio-opaque
Summary
It will be interesting to see if the popularity of LLRCs continues to rise in the future, especially amid mixed evidence that long term use of oral contraception can increase a woman’s risk for breast and cervical cancer. In addition, while devices may cost up to $1000 for insertion, the long-lasting nature of LLRCs and high rate of effectiveness in preventing unwanted pregnancies points to potential cost savings compared to monthly prescriptions for birth control pills, which are comparatively less effective even with perfect use. Improvements in the technology of LLRCs, including making these devices longer-lasting and potentially biodegradable, may serve to increase their popularity over time.
Sources
Biomaterials science: An Integrated Clinical and Engineering Approach, edited by yitzhak rosen and noel elman
https://www.drugs.com/drp/paragard-t-380a-intrauterine-copper-contraceptive.html
https://www.sciencedirect.com/topics/medicine-and-dentistry/contraceptive-implant
https://www.drugs.com/drp/paragard-t-380a-intrauterine-copper-contraceptive.html
https://www.plannedparenthood.org/planned-parenthood-columbia-willamette/long-acting-reversible-contraceptives-larcs
https://www.researchgate.net/publication/280944267/download
http://unmfamilyplanning.pbworks.com/w/file/fetch/119311257/Wu%20et%20all-Extended%20use%20of%20the%20IUD-review%20and%20recommendations.pdf
http://unmfamilyplanning.pbworks.com/w/file/fetch/119311257/Wu%20et%20all-Extended%20use%20of%20the%20IUD-review%20and%20recommendations.pdf
https://www.guttmacher.org/sites/default/files/images/contraceptivemethodchoicechart.png
https://www.guttmacher.org/fact-sheet/contraceptive-use-united-states
https://www.huffingtonpost.com/2015/02/24/iud-birth-control_n_6736218.html
http://freeiud.org/types-of-iuds/
https://www.nexplanon.com/what-is-nexplanon/