Contraception: Myths and Facts

In the second of a new series exploring some common misconceptions about conditions seen in general practice, GP Dr Toni Hazell debunks some myths about contraception – and explains some less well known facts

Myths

Myth 1: You usually have a delayed return to fertility after stopping contraception

Is it true there can be  a delay in return to fertility when the depot injection is stopped – the average is 5.5 months, and it can be up to one year. This must be clearly explained – every woman is different, and some will have no delay. Women who stop the depot but still need contraception should use another method from the date when their next injection would have been due; I have arranged more than one termination of pregnancy for a woman who assumed that she couldn’t get pregnant for a year after the last depot.

But no other method has a significant delay; fertility will return swiftly to how it would have been if the method was never used. This isn’t necessarily the same fertility that was there before the method started to be used, as the woman will be older and may have other issues such as obesity which can affect fertility.

Myth 2: Most contraceptives make you put on weight

Again, the depot is the exception to the rule here, being associated with weight gain. This is particularly an issue for those aged under 18 who have a body mass index (BMI) of over 30 kg/m¹ when they start using the method. Those women who gain more than 5% of their baseline weight in the first six months of depot use are most likely to experience continued weight gain².

But FSRH guidance is clear that there is no evidence of a causal relationship between use of any other method and weight gain. Weight gain is listed in the BNF as a side-effect of some methods, but that just means that it has been reported whilst using the method, not that it was caused by the method.

Myth 3: You need to give your body a break from contraception every now and then

This is a pervasive urban myth, which is potentially dangerous. There is no medical reason why women need a break from contraception, and the most likely outcome of such a break is an unwanted pregnancy. For combined hormonal contraception (CHC), having a break and restarting could increase the risk of a venous thromboembolism (VTE), as it is known that the risk of VTE is higher when CHC started, whether that is for the first time, or restarted after a break of at least one month³. Risks should of course be put into context – for every 10,000 women who use CHC for one year, there will be an extra 3 – 10 VTEs. This can be set against the benefits of reliable contraception, and the non-contraceptive benefits on dysmenorrhoea, menorrhagia and conditions such as endometriosis. VTE risk is much higher during pregnancy and the postpartum period.  

Myth 4: It’s bad for your body if you don’t have a period every month

It’s easy to forget how controversial the pill was, when it emerged as the first method of oral contraception in 1961. It was another six years before the Family Planning Act allowed clinics to advise unmarried women, and anecdotes about women sharing wedding rings to wear to doctor’s appointment were common. There was a perception that women wanted a monthly reminder that they weren’t pregnant, and the regular bleed was used in an attempt to persuade some religious authorities that the pill was no more than an extension of natural family planning.

A monthly ‘period’ when using CHC, is, of course not a period at all. It’s a withdrawal bleed, as the hormonal fluctuations of the menstrual cycle have been abolished by the use of hormonal contraception. It serves no biological purpose but is the most risky time for method failure; we know that women who are ultra-rapid metabolisers of oestrogen come close to risking ovulation at the end of a seven day hormone-free interval (HFI)⁴, and many more women will be at risk if they forget to restart on day eight.

FSRH guidance on CHC now recommends that all women are offered a tailored regime, which may include a four day break (instead of seven days), taken either monthly, after every third packet, or when breakthrough bleeding occurs. Other women will prefer continuous use, not stopping at all. This is likely to reduce contraceptive failure and is not thought to carry any extra risks. It may be particularly useful in women with obesity, for whom the risk of ovulation in the HFI is possibly higher³. Women should be informed that tailored pill taking is unlicensed but supported by FSRH guidance.

Myth 5: If you’ve had an ectopic, you can’t ever use a coil for contraception

The intrauterine device (IUD, colloquially known as a ‘coil’) is an effective method of contraception, with a typical failure rate of only 0.8% for the copper IUD (Cu-IUD), and 0.2% for the levonorgestrel IUD (LNG-IUD). It is a UK Medical Eligibility Criteria (UKMEC) category 1 (no restrictions on use) for those who have had a previous ectopic, and it can be inserted immediately after an ectopic pregnancy⁵ (if there is no pelvic infection), yet the urban myth that the coil increases the rates of ectopic pregnancy is pervasive.

The IUD prevents the vast majority of pregnancies and so a woman who is using an IUD has a much lower absolute risk of both intrauterine pregnancy and ectopic pregnancy. However, if the IUD fails, the relative risk of ectopic pregnancy is higher, because the IUD is better at preventing intrauterine pregnancies than it is at preventing ectopic pregnancies. In the general population, around 1% of all pregnancies will be ectopic – in the population of women whose IUD has failed, the ectopic rate could be as high as 53%⁵. It is therefore essential that any woman who has a positive pregnancy test with an IUD in situ be referred for an urgent scan to ensure that the pregnancy is intrauterine.

Facts

Fact 1: The implant is by far the most reliable method of contraception

When considering contraceptive efficacy, we need to look at efficacy during perfect use and typical use. Any method which requires regular user action, will have a lower typical efficacy than the perfect use efficacy which is more theoretical. It follows that the typical efficacy for long-acting reversible contraceptives (LARCs), will be higher than for those such as the pill or patch, which require user input.  The most effective contraceptive that we have is the implant, with a typical failure rate of 0.05%⁶, or 1 in 2000 women in the first year of use. By comparison, typical failure rates for other methods include 6% for the depot injection, 9% for the patch, ring or pill, and 18% for condoms. Female sterilisation, considered by some to be a ‘gold standard’ method, has a failure rate of 0.5% in the first year – 10 times that of the implant and 2.5 times that of the levonorgestrel IUD. A woman considering sterilisation might want to talk to her partner about shared contraceptive responsibilities, as the typical first-year failure rate for vasectomy is much lower at 0.15%.

Fact 2: Some contraceptives can be used as part of HRT

The Mirena® brand of the 52mg LNG-IUD has a licence for use as the progestogenic component of HRT, with a duration of four years. The other brands of 52mg LNG-IUD (Levosert®  and Benilexa®) are not licensed for this purpose but are essentially the same device. The 2023 update of the FSRH guidance on IUDs made it clear that any 52mg LNG-IUD can be used for endometrial protection in HRT, and that this can be done for five years. While this is unlicensed, the FSRH is the key body that writes guidance on contraception in the UK, and it is therefore medicolegally safe to follow their advice. The 52mg LNG-IUDs all have a licence for contraception which is longer than five years, but women who are using them for both purposes (HRT and contraception) should have them replaced at five years.

Fact 3: The copper coil can be used for emergency contraception

The Cu-IUD is the most effective method of emergency contraception (EC), with an overall pregnancy rate of 0.1%. Oral methods of EC are associated with overall pregnancy rates of 1-2%⁷. Uptake is however anecdotally low, and it can be challenging to plan a service which can provide a Cu-IUD fitting at very short notice, with demand that may vary. Other factors affecting update of the Cu-IUD for EC include a lack of understanding or awareness of the method and concerns about adverse effects^8,9. If a woman chooses a Cu-IUD for EC, but it cannot be fitted immediately, she should also be given oral EC as a safety-net, in case she changes her mind and does not return for the fitting, or the IUD cannot be fitted.

Fact 4: Patients can give themselves the contraceptive injection

The depot can be given as an intramuscular (IM) or a subcutaneous (SC) injection; the latter can be given by patients at home. While there are slight differences in licensing, the FSRH advises that both brands (Depo-Provera®  IM and Sayana-Press®  SC) should be given every 13 weeks, with a week’s grace – ie a late injection can be given up to 14 weeks after the last one, with no need for extra precautions such as condoms. Sayana-Press®  can be prescribed for self-administration at home, with no difference in continuation rates compared to administration by a healthcare professional. It is advised that there always be another adult present when self-administration is done (in case of an adverse reaction); women can be taught to self-administer by a healthcare professional, or can watch the video on the manufacturer’s website, or via other online sources.

Fact 5: Some contraceptives reduce your risk of common cancers

Women often have concerns that a hormonal method of contraception may increase their risk of cancer. For most women the absolute increase in risk is tiny. For example, current CHC use is associated with a relative risk of breast cancer of 1.19¹⁰. For an average woman aged 20 – 24, the background risk of breast cancer is 33 per 100,000 per year, so a 1.19 increase in relative risk gives around six extra cases per 100,000 women per year. The risk rises with increased background risk – this can happen with age or with family history and so it is a good idea to take a family history of breast cancer when starting a hormonal method of contraception, and to consider a genetics referral if there is a strong family history¹¹.

This small increase, which is lost within five years of stopping CHC, should however be set against a significant reduction in ovarian cancer. Women who have used the combined pill for at least 10 years will reduce their risk of ovarian cancer by 50%; the effect increases with duration of pill use and persist for at least 30 years after the pill is stopped³. Ovarian cancer is more common than breast cancer in the 20 – 24 cohort, and so for this group, the combined pill is likely to have an overall beneficial effect in terms of cancer risk. CHC is also associated with a reduction in colorectal and endometrial cancer (as well as a small increase in cervical cancer) and we mustn’t forget the increased risk of cancer from lifestyle causes, which often outweighs that from hormonal contraception. For example, it is estimated that 400 cases of breast cancer are caused each year in the UK by the combined pill, compared to 4,400 from alcohol excess.

Dr Toni Hazell is a GP in London. She has a long interest in women’s health and has previously been worked in contraception and sexual health clinics. She is on the board of the Primary Care Women’s Health Forum.

References (all accessed 23.4.24 unless otherwise stated)

1. FSRH Clinical Guideline: Overweight, Obesity and Contraception (April 2019).
2. FSRH Clinical Guideline: Progestogen-only Injectable (December 2014, Amended July 2023).
3. FSRH Clinical Guideline: Combined Hormonal Contraception (January 2019, Amended October 2023).
4. Routledge. Contraception today. Ninth edition. 2020.
5. FSRH Clinical Guideline: Intrauterine contraception (March 2023, Amended July 2023).
6. NICE CKS. Contraception – assessment. Jan 2024.
7. FSRH Clinical Guideline: Emergency Contraception (March 2017, amended July 2023).
8. Simmons, R. G., Baayd, J., Elliott, S. A., Cohen, S. R. & Turok, D. K. Improving access to highly effective emergency contraception: an assessment of barriers and facilitators to integrating the levonorgestrel IUD as emergency contraception using two applications of the Consolidated Framework for Implementation Research. Implementation Science Communications 3, (2022).
9. Westley, E. & Glasier, A. Emergency contraception: dispelling the myths and misperceptions. Bulletin of the World Health Organization 88, 243 (2010).
10. Cancer Research UK. Ovarian cancer incidence statistics.
11. NICE. CG165. Familial breast cancer: classification, care and managing breast cancer and related risks in people with a family history of breast cancer.  Nov 2023.