Can Hormonal IUDs Cause Uterine Scarring? New Research Explained with Dr. Heather Huddleston
Can hormonal IUDs cause uterine scarring? Could long-term hormonal IUD use affect fertility? These are important questions that many women are asking, especially as hormonal IUDs have become one of the most commonly used forms of contraception.
In this discussion, Dr. Natalie Crawford is joined by reproductive endocrinologist Dr. Heather Huddleston, Professor at UCSF, to review the latest research on hormonal IUDs and intrauterine adhesions (uterine scarring). Together, they explain what researchers have observed, what current evidence suggests, and why more research is needed before any conclusions can be made about an individual’s risk.
Hormonal IUD Side Effects: New Research on Uterine Scarring with Dr. Heather Huddleston
The FeRTILE Study (Fertility, Reproductive outcomes & Time to conception – Impact of Longterm IUD Exposure) is a UCSF research study examining fertility and time to conception following long term IUD use.
The link to the pre-print will be added when available.
Researchers are recruiting women aged 25–35 who have never been pregnant, have used an IUD (progestin or Copper) or another form of contraception, and are planning to conceive. Participation involves an online baseline questionnaire followed by brief quarterly surveys over one year. All participation is remote and confidential, and participants can earn up to $75 for completing the study surveys.
Please click the link to take a short eligibility survey: https://redcap.ucsf.edu/surveys/?s=LYXF3LYF8WKCKKP3
Timestamps:
00:00 Hormonal IUDs & Uterine Scarring: New Research
01:07 Why Researchers Studied Hormonal IUDs
02:15 Hormonal IUD vs Copper IUD: What's the Difference?
04:16 Can Hormonal IUDs Cause Uterine Scarring?
06:26 How Uterine Scarring Can Affect Fertility
07:34 New Hormonal IUD Research Explained
08:40 How the Uterine Scarring Study Was Conducted
10:19 Study Results: Hormonal IUD & Uterine Adhesions
13:07 Does Long-Term Hormonal IUD Use Increase Risk?
15:34 Why More Hormonal IUD Research Is Needed
18:01 The FERTILE Study: Who Can Participate?
19:10 Long-Term Hormonal IUD Use & Fertility
20:35 Association vs Causation: What the Research Shows
21:15 Why This Fertility Study Needs More Participants
22:43 Is Long-Term Hormonal IUD Use Safe?
24:48 Final Thoughts on Hormonal IUD Safety & Fertility
Why Researchers Began Studying Hormonal IUDs
The idea for this research did not come from a single patient or isolated case. Instead, Dr. Huddleston and her colleagues began noticing what appeared to be a pattern among patients diagnosed with intrauterine adhesions. While they were unsure whether this represented a true association or simply reflected the growing popularity of hormonal IUDs, the observation prompted an important research question.
Patient questions also played a role. Many women specifically asked whether hormonal IUDs could contribute to uterine scarring, highlighting the need for better data.
Why the Focus Is on Hormonal IUDs
One of the first questions patients ask is why researchers are studying hormonal IUDs rather than copper IUDs.
Hormonal IUDs release levonorgestrel directly into the uterus, causing the uterine lining (endometrium) to become very thin. This is one of the reasons many users experience lighter periods or stop having periods altogether. While this is often considered a beneficial effect, researchers wondered whether this altered environment might also influence how the uterine lining heals after an injury.
Copper IUDs work differently. Because they do not release hormones or significantly change the biology of the uterine lining, researchers have not observed a similar signal suggesting an association with uterine adhesions.
Importantly, the doctors emphasize that there is currently no evidence suggesting the same concern exists with copper IUDs.
The Biology Behind the Question
Researchers believe there is biologic plausibility for studying this question because estrogen plays a major role in helping the uterine lining grow, regenerate, and heal.
Hormonal IUDs expose the uterus to high levels of progestin, which suppresses the normal effects of estrogen within the endometrium. The question researchers are asking is whether a uterine lining in this altered hormonal state heals differently if an injury occurs.
At this point, this remains a hypothesis—not a proven mechanism—but it provides a scientific reason to investigate the question further.
What the New Study Found
Dr. Huddleston’s team recently completed a case-control study examining whether prior hormonal IUD use was more common among patients diagnosed with intrauterine adhesions.
Researchers reviewed six years of hysteroscopy procedures performed at their center and identified more than 300 patients with uterine adhesions. They then compared those patients with carefully selected control groups to determine whether previous hormonal IUD use differed between groups.
The study found that previous hormonal IUD use was approximately three times more common among patients with uterine adhesions than among comparable patients without adhesions.
However, the researchers emphasize an important point:
This study shows an association—not proof that hormonal IUDs cause uterine scarring.
The findings suggest the question deserves further investigation but cannot establish cause and effect.
What About Long-Term Hormonal IUD Use?
One of the most interesting findings from the study involved duration of use.
The association appeared much stronger among women who had used a hormonal IUD for more than five years. Researchers also observed a stronger association among women who had not previously had a baby (nulliparous women).
These findings are especially important because contraceptive practice has changed over time. Hormonal IUDs are now approved for longer durations of use than when they were originally introduced, and they are commonly used by women before their first pregnancy.
Researchers believe more data are needed to understand whether long-term exposure affects fertility differently than shorter-term use.
Why More Research Is Needed
Although the case-control study found an association, it cannot answer one of the most important questions women have:
What is my personal risk?
Researchers cannot currently say whether this outcome occurs in one out of 1,000 women, one out of 100 women, or another frequency entirely.
Answering that question requires a prospective study that follows women over time instead of looking backward after an outcome has already occurred.
The FERTILE Study
To answer these unanswered questions, Dr. Huddleston and her colleagues have launched the FERTILE Study (Fertility, Reproductive Outcomes and Time to Conception: The Impact of Long-Term IUD Exposure).
The study is enrolling women across the United States who are beginning to try to conceive, including both women who have used hormonal IUDs and women who have not. Participants complete surveys over time so researchers can better understand pregnancy outcomes and estimate the true risk of uterine adhesions and other fertility outcomes.
The link to the pre-print will be added when available.
The researchers emphasize that broad participation is essential because large numbers of participants are needed to accurately estimate risk.
Researchers are recruiting women aged 25–35 who have never been pregnant, have used an IUD (progestin or Copper) or another form of contraception, and are planning to conceive. Participation involves an online baseline questionnaire followed by brief quarterly surveys over one year. All participation is remote and confidential, and participants can earn up to $75 for completing the study surveys.
What Does This Mean for Patients Today?
Dr. Crawford and Dr. Huddleston are clear that this research should not be interpreted as a recommendation to avoid or remove hormonal IUDs.
Hormonal IUDs remain an excellent and highly effective contraceptive option for many women.
Instead, the goal of this research is to generate the evidence needed to provide better counseling and informed consent. If future studies identify specific risk factors—such as duration of use or particular patient populations—physicians may eventually be able to provide more individualized recommendations.
Until then, researchers continue to emphasize that more high-quality evidence is needed before changing clinical practice.
The Bottom Line
Hormonal IUDs continue to be an effective form of contraception for many women. However, new research has identified an association between prior hormonal IUD use and intrauterine adhesions that deserves further study.
At this time, researchers cannot conclude that hormonal IUDs cause uterine scarring or infertility. Instead, the findings highlight the need for larger prospective studies to determine whether an association exists, estimate individual risk, and better understand the effects of long-term hormonal IUD use on fertility.
As both physicians emphasize throughout the discussion, the ultimate goal is not to discourage hormonal IUD use—it is to ensure women have the best possible evidence to make informed decisions about their reproductive health.