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How Hormonal Intrauterine Devices (IUDs) Prevent Pregnancy
The topic I chose to research for my STEAM project is how hormonal intrauterine devices (IUDs) work to prevent pregnancy. During the reproductive unit we talked about oral birth control pills, but not specifically IUDs. The course objectives this project ties back to are “Describe how ovulation, menses, pregnancy, and spermatogenesis are hormonally regulated” and “Know the structure and function of reproductive organs”. An IUD is a form of contraception placed directly in the uterus and is used widely throughout the world due to it being effective and safe. Hormonal IUDs (IUDs that contain progestin) have between a 0.1% to 0.2% failure rate within the first year of use (Tinelli, Andrea, et al.).The progestin found in hormonal IUDs is very similar to a hormone naturally made in our body, progesterone (Planned Parenthood) and helps us tie back to the course objective “Describe how ovulation, menses, pregnancy, and spermatogenesis are hormonally regulated”. Hormonal IUDs work as birth control by thickening cervical mucosa and impeding sperm from reaching the upper genital tract (Mishell Jr., D. R.). IUDs have also been said to work to inhibit blastocyst (early stage of the embryo) implantation in the uterus since the IUD physically being in the uterus makes it an unfavorable environment for the egg (Tinelli, Andrea, et al.).
IUDs are considered to be spermicidal and prevent fertilization by preventing sperm from reaching the egg (Mishell Jr., D. R.). IUDs are shaped like the letter “T” and made out of plastic, however there are non hormonal options out there that are made out of copper. Not only do hormonal IUDs thicken cervical mucus preventing sperm from traveling to the egg, but hormonal IUDs can also inhibit ovulation. This causes the egg to be prevented from leaving the ovaries, meaning there would not be an egg for the sperm to fertilize (Planned Parenthood). IUDs can be in place anywhere from three years even up to eight years depending on which brand of IUD is placed. There are four brands of hormonal IUDs available in the United States that all work for different amounts of time. Skyla works up to three years, Kyleena works up to five years, and Mirena and Liletta both work up to eight years (Planned Parenthood). Each brand of hormonal IUDs work to prevent pregnancy the same way, which is using progestin to thicken cervical mucosa to prevent sperm from reaching an egg, as well as preventing ovulation in some cases. Certain brands of hormonal IUDs have more amounts of progestin in them, but this doesn’t change how effective they are, only how long the IUD itself lasts (Planned Parenthood).
I decided to use a comic as my form of art to show how hormonal IUDs work to prevent pregnancy. The comic shows the IUD being placed in the uterus and releasing progestin in the first panel. The vagina, cervix, uterus, IUD, and ovaries are labeled so the anatomy is easier to follow and also ties back to the course objective “Know the structure and function of reproductive organs”. The second panel shows cervical mucosa in the cervix thickening due to the progestin. The thickened mucus in the cervix blocks sperm from reaching the egg in the next picture. The fourth panel shows the egg staying in the ovary and not being released. The last panel shows that the hormonal IUD does everything in the first four panels to prevent pregnancy.
References
Tinelli, A., Tinelli, R., Malvasi, A., Cavallotti, C., & Tinelli, F. G. (2006). The intrauterine device in modern contraception: Still an actuality? European Journal of Contraception & Reproductive Health Care, 11(3), 197–201. https://doi.org/10.1080/13625180600759755
Mishell Jr., D. R. (2004). Intrauterine Contraception: Benefits to Patients. Journal of Family Practice, S9–S14.
MACMILLAN, C. (2023, October 4). What Women Should Know About Intrauterine Devices (IUDs). Yale Medicine. Retrieved April 11, 2025, from https://www.yalemedicine.org/news/intrauterine-devices-iud
Hormonal IUDs. (n.d.). Planned Parenthood. Retrieved April 14, 2025, from https://www.plannedparenthood.org/learn/birth-control/iud/hormonal-iuds
This STEAM project explores how hormonal intrauterine devices (IUDs) function to prevent pregnancy, linking to course objectives on hormonal regulation of reproductive processes and the structure and function of reproductive organs. Hormonal IUDs are a widely used and highly effective form of long-acting reversible contraception, with a failure rate between 0.1% and 0.2% in the first year of use (Tinelli et al.). These devices are T-shaped and made of plastic, and they release a hormone called progestin, which is similar to the body’s naturally produced progesterone (Planned Parenthood).
The primary way hormonal IUDs prevent pregnancy is by thickening the cervical mucus, which blocks sperm from passing through the cervix and reaching the upper reproductive tract (Mishell Jr.). This physical barrier greatly reduces the chances of sperm meeting an egg. Hormonal IUDs may also prevent ovulation in some users, meaning that no egg is released for sperm to fertilize (Planned Parenthood). This works because the presence of the IUD in the uterus can create an environment that is unfavorable for implantation, further reducing the chance of pregnancy.
There are four hormonal IUD brands available in the United States, each offering protection for different durations: Skyla (3 years), Kyleena (5 years), Mirena (8 years), and Liletta (8 years) (Planned Parenthood). Although these IUDs vary in their progestin levels and duration of use, they all function similarly by altering the cervical mucus and, in some cases, inhibiting ovulation. This project helps convey the understanding of hormonal contraceptive methods and illustrates how they relate to the hormonal control of ovulation, menstruation, and pregnancy.