News
Copper coil vs Mirena: Which is right for you?

Article produced in association with Spital Clinic
Both the copper coil and the Mirena are more than 99 per cent effective as contraceptives — but they work in completely different ways, have opposite effects on periods, and suit very different people.
With the FSRH’s May 2024 licence extension for the Mirena now in effect, this guide covers the five key differences using up-to-date UK evidence, not the older guidance that many sources still repeat.
How Each Device Works
The FSRH March 2023 guideline set out the terminology now used across UK clinical practice: the copper intrauterine device (Cu-IUD) and the levonorgestrel intrauterine system (LNG-IUD).
The copper coil works by releasing copper ions that are toxic to sperm, preventing fertilisation. It contains no hormones at all, making it a strong option for women who cannot or do not want hormonal contraception.
The Mirena — the most widely prescribed 52mg LNG-IUD in the UK — thickens cervical mucus to block sperm, thins the uterine lining, and may suppress ovulation, though most users continue to ovulate normally.
According to Hull University Teaching Hospitals NHS Trust, the hormone levels it produces are lower than those from the combined contraceptive pill — relevant for women advised to avoid higher-dose hormonal methods.
The hormone-free nature of the Cu-IUD is its defining advantage for some; the localised hormonal action of the LNG-IUD is its defining advantage for others.
According to NHS guidance on the copper coil, neither device interacts with medicines or herbal remedies, and both can be fitted in women who have never been pregnant.
The way each device works also determines what it does to periods — often the deciding factor.
Effectiveness and Duration
The NHS confirms both devices prevent pregnancy in more than 99 per cent of users. When it comes to contraceptive effectiveness, there is no meaningful difference between them.
Where they differ significantly is duration. The copper coil lasts up to 10 years, and one fitted in a woman aged 40 or over can remain in place until menopause under FSRH March 2023 guidance.
For the Mirena, the picture changed in May 2024: the FSRH CEU statement on extended LNG-IUD use confirmed that all 52mg LNG-IUDs — including the Mirena, Levosert, and Benilexa — are now licensed for eight years of contraceptive use, up from five under previous guidance.
When the Mirena is used as part of HRT, it protects the uterine lining for up to five years before requiring replacement. Smaller-dose devices such as Kyleena (20mcg) are licensed for five years, and Jaydess for three.
Both are long-acting reversible contraceptives — fertility returns immediately after removal, with no delay or washout period. Both are available without a GP referral through the coil insertion and removal service at Spital Clinic.
What Each Device Does to Periods
The most important practical difference is what each device does to periods — and they go in opposite directions.
The copper coil typically makes periods heavier, longer, and more painful; the NHS notes this may ease after a few months, but heavier bleeding is one of the most common reasons for early removal.
Both devices can cause irregular spotting in the first three to six months after fitting.
The Mirena does the opposite.
According to Hull University Teaching Hospitals NHS Trust, it reduces monthly blood loss by 86 per cent at three months and by 97 per cent at twelve months.
Nine in ten women who use it for heavy periods see a significant reduction; around 20 per cent have no bleeding at all; and 80 per cent report meaningful pain relief.
NHS information on the hormonal coil confirms that periods often become lighter, shorter, and less painful — with many users finding they stop entirely after the initial settling-in period.
For women whose choice of contraception is being shaped by troublesome periods, those statistics make the direction of the decision clear.
For women with already disrupted cycles, it is worth booking a private specialist assessment before deciding — for this group, the choice of coil is as much a treatment decision as a contraceptive one.
Unlike the copper coil, the Mirena is licensed as a first-line treatment for menorrhagia — heavy or prolonged bleeding defined as losing more than 80ml per cycle or periods lasting longer than seven days.
In around half of cases, heavy periods have no identifiable structural cause, making the Mirena’s targeted local action particularly useful: it reduces bleeding at the endometrial level without surgery, general anaesthesia, or high-dose systemic hormones, and offers a non-surgical alternative to procedures such as endometrial ablation.
Side Effects, Risks, and Who Cannot Use Each Device
Both devices carry the same procedural risks. Pelvic infection affects around 1 in 100 women in the first three weeks; expulsion happens in roughly 1 in 20; and uterine perforation occurs in approximately 2 in 1,000 fittings — slightly higher in women breastfeeding within six months of delivery. Ectopic pregnancy, though rare, is a risk if either device fails.
The side-effect profiles diverge beyond those shared risks.
The copper coil carries no hormonal side effects — heavier periods are its main downside. The
Mirena may cause acne, headaches, mood changes, breast tenderness, and ovarian cysts; most resolve without treatment, but they are worth considering for anyone sensitive to progestogen.
The Mirena is also unaffected by vomiting, diarrhoea, or most drug interactions.
Each device has its own contraindications. Neither should be fitted in the presence of an active sexually transmitted infection or unexplained uterine bleeding.
The Mirena is not suitable for women with a history of breast cancer, certain liver conditions, serious cardiovascular disease, or certain uterine abnormalities.
The copper coil, meanwhile, can be used as emergency contraception if fitted within five days of unprotected sex — the only intrauterine option for post-coital protection.
The Fitting Procedure and What to Expect
The fitting procedure is the same for both devices: a 10 to 15 minute clinical appointment, ideally towards the end of a period, though it can happen at any point in the cycle.
The full appointment takes around 30 minutes. Local anaesthetic gel or spray is used to manage discomfort, and the NHS advises taking ibuprofen or paracetamol about an hour beforehand.
No surgery or general anaesthetic is needed. Some cramping and light spotting in the days after fitting is normal and usually settles within a week. Neither device requires you to have had children previously.
Fertility returns immediately after removal of either device — there is no waiting period before trying to conceive.
For most women, the choice between the copper coil and the Mirena comes down to one question: are hormones acceptable or not?
The copper coil suits women who want hormone-free contraception, those who cannot use progestogen, and those who need emergency post-coital protection.
The Mirena suits women who want lighter or absent periods, those managing menorrhagia, and those using it as the progestogen component of HRT.
Both offer equivalent contraceptive effectiveness and full reversibility.
The FSRH’s May 2024 extension of the Mirena’s licence to eight years makes it a stronger long-term option than many comparisons suggest — worth knowing if the information you have found is based on older guidance.
This article is produced for informational purposes only and does not constitute medical advice, diagnosis or treatment. Clinical guidance referenced reflects published NHS and FSRH standards as at March 2025. Individual circumstances vary; readers are advised to consult a qualified healthcare professional before acting on any information in this article.
This piece was produced in association with Spital Clinic, which provided background clinical information for editorial purposes. Hyperlinks to external sources are included for reference only and do not represent an endorsement of any product, service or organisation.
Wellness
Congress urged to invest over $20bn to close women’s health gap

Congress is being urged to invest US$20bn over 10 years to close the women’s health gap.
The American College of Obstetricians and Gynecologists, the Society for Women’s Health Research and the Women First Research Coalition have unveiled the National Strategy to Close the Women’s Health Gap.
The framework calls for a coordinated national effort to improve women’s health research, care and outcomes.
It says women make up more than half of the US population, but their health needs across conditions and life stages have been understudied and underserved for decades.
Kathryn Schubert, president and chief executive of the Society for Women’s Health Research, said: “The women’s health gap has persisted for far too long.
“This strategy offers Congress a road map to improve health outcomes, drive innovation, and build a healthier future for women, families, and communities.”
The strategy notes that Congress required women to be included in National Institutes of Health-funded clinical research through the NIH Revitalization Act in 1993.
However, it says major gaps remain in women’s health research, clinical care and how evidence is put into practice.
The plan proposes US$7bn for research and innovation, including expanded federal investment in women’s health research across the NIH, VA, DoD and the Advanced Research Projects Agency for Health.
It would also establish a Women’s Health Research Interdisciplinary Fund at the NIH and create a national network of Women’s Health Centers of Excellence.
The centres would aim to accelerate the translation of research into clinical care and serve as training sites for researchers and clinicians.
A further US$1bn would be used for regulatory coordination and modernisation, including cross-agency collaboration and work to address sex differences in drug and treatment approvals.
Sex differences are biological differences between females and males that can affect disease risk, symptoms, treatment response and side-effects.
The funding would also support updated NIH tracking systems for women’s health research investment and publication standards on how sex as a biological variable is considered in research.
The strategy calls for US$4bn for data and evidence infrastructure, including a public-private partnership focused on women’s midlife health data.
It would also convene a public workshop to review existing women’s health research datasets and develop common data elements to fill gaps and make datasets more widely available.
Another US$7bn would go towards strengthening the clinical and research workforce.
This would include career pathways, loan repayment programmes, a women’s health clinical workforce loan repayment programme modelled on the National Health Service Corps and interdisciplinary training.
The workforce measures would include particular emphasis on rural and underserved areas.
The final US$1bn would support public awareness and education campaigns to improve health literacy, preventive care and participation in women’s health research.
Health literacy means a person’s ability to find, understand and use health information to make decisions about care.
The campaigns would use digital and traditional media developed in consultation with patient advocacy organisations and relevant medical societies.
Sandra E Brooks, chief executive of the American College of Obstetricians and Gynecologists, said: “Closing the women’s health gap requires not only funding research, but also investment in the people who conduct that research and those who translate research findings and discoveries into better patient care.
“Strengthening the women’s health research and clinical workforce is critical to accelerating the innovation needed to improve health outcomes for women.”
The strategy says women have higher annual out-of-pocket healthcare costs than men and live 25 per cent of their lives in poorer health.
Supporters say this strengthens the economic and public health case for long-term congressional investment.
The framework has been endorsed by organisations across women’s health, ageing, heart disease, autoimmune disease, cancer, reproductive medicine and neurological conditions, including the Women’s Alzheimer’s Movement at Cleveland Clinic, the National MS Society and UsAgainstAlzheimer’s.
Hormonal health
Stardust period tracker shares health data, study reveals
Stardust shared sensitive period tracking data with third-party analytics firms, according to new privacy research from Mozilla.
The findings expose a privacy divide in femtech, where users often trust apps with highly sensitive reproductive health information.
The research was carried out by Mozilla’s Privacy Not Included team, which tested several period tracking apps.
It found that Stardust, a period tracker used by millions, shared users’ reproductive health data with analytics companies, a practice the research said contrasted with its privacy-first marketing.
Analytics companies collect and examine information about how people use digital products, often to help businesses understand user behaviour or improve marketing.
The findings raise questions about whether privacy promises made by health apps match what happens to users’ data.
According to research reported by TechCrunch, one other period tracking app tested by Mozilla received what researchers called a “squeaky clean” rating, suggesting similar services can operate without sharing sensitive health data in the same way.
Period tracking apps have come under greater scrutiny in the US since the 2022 overturning of Roe v Wade, which removed federal constitutional protection for abortion.
Some users and privacy advocates have warned that menstrual and reproductive health data could potentially be sought in legal cases.
The research also points to a broader regulatory problem for consumer health apps.
In the US, many health apps are not covered by HIPAA, the health privacy law that applies to medical providers and some healthcare organisations.
That means some consumer apps may be able to collect, share or monetise sensitive health data under rules that differ from traditional healthcare privacy protections.
The femtech market, estimated in the report at US$50bn, has grown quickly, but privacy regulation has not always kept pace with app development.
Stardust had not publicly responded to Mozilla’s findings at the time of the original report, and its privacy policy remained live on its website.
The issue is particularly sensitive for period tracking because the data can reveal patterns around fertility, pregnancy, contraception and reproductive health.
Mozilla’s wider Privacy Not Included initiative has examined consumer technology products for privacy and security concerns since launching in 2017, including connected devices, children’s toys and health apps.
The findings come as US lawmakers continue to debate stronger federal privacy rules for sensitive health information collected by consumer apps.
The American Data Privacy and Protection Act, which has been stalled in Congress since 2023, includes provisions addressing sensitive health information collected by consumer apps.
Experts have also warned that anonymised health data can sometimes be re-identified when combined with other information, such as location data.
Re-identification means linking supposedly anonymous data back to a specific person.
A 2019 study found that menstrual cycle data combined with location information could identify individual users with high accuracy.
State-level privacy laws in places such as California, Virginia and Colorado have also given consumers new rights around personal data, although enforcement can vary.
Privacy advocates say the research underlines the need for clearer data practices, stronger safeguards and greater transparency in femtech.
For users, the findings are a reminder that health apps do not automatically protect health information in the same way as healthcare providers.
The report suggests period tracker companies that put privacy first may be better placed to build trust in a market where long-term use depends on confidence.
Mozilla’s investigation suggests privacy promises in femtech do not always match practice, and that period trackers can function without sharing sensitive user data in the same way.
News
Juno Bio secures US$3.8m for precision diagnostics

Juno Bio has secured US$3.8m to expand its diagnostics platform for vaginal health and reproductive care.
The funding round was led by Ada Ventures, with participation from Artesian, Entrepreneur First and Illumina Accelerator.
The women’s health startup said the seed funding will support the launch of its first CLIA-certified sequencing laboratory in Oakland, California, and a new clinical vaginal microbiome and STI test for healthcare providers.
CLIA certification refers to US laboratory standards for testing human samples used in diagnosis, prevention or treatment decisions.
Dr Leighton Turner, co-founder and chief scientific officer of Juno Bio, said: “The vaginal microbiome is still one of the least understood systems in the body at a clinical scale.
“With our lab, we’re starting to build a measurement standard that clinicians can actually use.
“We believe the level of detail from this kind of testing can meaningfully improve how vaginal healthcare is provided.”
The company is developing precision diagnostics for vaginal health, where patients can experience recurring symptoms, inconsistent diagnoses and treatments based on trial and error.
Juno Bio said bringing testing in-house gives it greater control over the process, from sample handling to results, while allowing it to refine its technology and build what it says is one of the largest datasets focused on the vaginal microbiome.
The vaginal microbiome is the community of bacteria and fungi that naturally live in the vagina. Changes in this balance can be linked to infections, symptoms and wider reproductive health issues.
Juno Bio’s newly launched clinical test examines the wider vaginal microbiome and screens for four common sexually transmitted infections, or STIs.
Rather than looking for a single cause, the test is intended to give clinicians a broader picture of what may be contributing to symptoms.
Juno Bio says this matters because multiple infections can occur at the same time and microbiome changes may be linked to fertility, menopause or recurrent infections.
Dr Anna Powell of Johns Hopkins said: “Vaginal microbiome testing has the potential to significantly reshape how we understand and manage vaginal health, particularly for patients with recurrent or unexplained symptoms.
“While the field is still evolving, advances in sequencing and data interpretation are moving us closer to a future where more personalised, microbiome-informed care can complement existing diagnostic approaches.”
Check Warner, co-founding partner at Ada Ventures, added: “Juno Bio is setting a new standard for how vaginal health is understood and managed.
“What they’ve built at this stage, with this level of capital efficiency, is exceptional.
“We’re proud to support the team as they scale their clinical infrastructure and continue leading innovation in this critically underserved category.”
Insight2 weeks agoWomen with PMOS should have annual NHS checks, new guidance says
Diagnosis1 week agoTwo “gamechanger” tests set to speed up endometriosis diagnosis on the NHS
News2 days agoNew menopause drug approved for use by NHS in Scotland
Cancer1 week agoThousands of women could avoid painful cancer exam with new AI blood test
News2 weeks agoBreast cancer biosensor and low-cost ultrasound startups win women’s health AI competition
Entrepreneur1 week agoApplications open for the third W Accelerate with Merck KGaA and M Ventures
News2 weeks agoClue spotlights seven women’s health journeys in new campaign
Fertility1 week agoOlder women face lower chance of fertility treatment working, even with donor eggs, study finds












