Dr Annabel Forsythe and Valerie Warner Findlay Explore the Latest Recommendations from the FSRH About Contraceptive Use in Women who are Overweight or Obese
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Find key points and implementation actions for STPs and ICSs at the end of this article
All women of reproductive age should have access to safe and effective contraception. Currently, over one-half of adult women in the UK are overweight or obese, with numbers expected to increase over time.1–3 Clinicians may have questions and concerns regarding which contraceptive methods are most appropriate for women with raised body mass index (BMI), and what other factors might influence contraceptive choice in this group of women.
Although the evidence in this area is limited, adult women with a BMI ≥25 kg/m2 appear to have an equivalent or higher risk of unintended pregnancy compared to women of normal weight (weight categories are defined by BMI in Table 1). Most women with obesity are likely to ovulate regularly and have similar fertility to women without obesity.
In studies comparing rates of contraceptive use among women with raised BMI and women without raised BMI, some studies showed no difference in use of contraception while others showed that women with raised BMI are less likely to use contraception than women with normal BMI.4 Women with obesity, particularly those with co-morbidities, are at significantly higher risk of pregnancy-related complications so pregnancy planning and pre-pregnancy optimisation of weight are especially important.4 It is therefore essential that women who are overweight or obese have access to appropriate contraception and related support if and when they want it.
Table 1: Definition of Weight Categories and Body Mass Index4
|Weight Category||Body Mass Index (BMI) (kg/m2)|
|* Sometimes referred to as severely obese|
Faculty of Sexual & Reproductive Healthcare. Overweight, obesity and contraception. FSRH, 2019. Available at: www.fsrh.org/documents/fsrh-clinical-guideline-overweight-obesity-and-contraception/
Reproduced with permission
Using available evidence and the consensus opinion of experts, the Faculty of Sexual & Reproductive Healthcare (FSRH) has developed a guideline entitled Overweight, obesity and contraception to support clinicians when advising women who are overweight or obese in making informed choices regarding contraception.4
The guideline primarily focuses on:
- effectiveness and safety of available contraception for women with BMI ≥25 kg/m2
- the interrelationship between contraception and weight
- practical considerations relating to contraception in women with raised BMI
- contraception during use of weight loss medication and after bariatric surgery.
The new guideline provides method-specific information on effectiveness, safety, health benefits, weight gain, and practical considerations about use. It also reminds clinicians to consult the UK Medical Eligibility Criteria for Contraceptive Use (UKMEC), which offers guidance as to safe use of contraception for people with health conditions including obesity, history of bariatric surgery, and obesity as one of multiple risk factors for cardiovascular disease5 (see Table 2).
The UKMEC does not consider multiple conditions simultaneously, so in the presence of multiple risk factors, assessment of a woman’s medical eligibility for contraception requires particularly careful individual clinical judgment supported by available guidance and evidence.
Table 2: UK Medical Eligibility Criteria for Contraceptive Use (UKMEC)5 Categories
|UKMEC||Definition of Category|
|Category 1||A condition for which there is no restriction for the use of the method.|
|Category 2||A condition where the advantages of using the method generally outweigh the theoretical or proven risks.|
|Category 3||A condition where the theoretical or proven risks usually outweigh the advantages of using the method. The provision of a method requires expert clinical judgment and/or referral to a specialist contraceptive provider, since use of the method is not usually recommended unless other more appropriate methods are not available or not acceptable.|
|Category 4||A condition which represents an unacceptable health risk if the method is used.|
Faculty of Sexual & Reproductive Healthcare. UK medical eligibility criteria for contraceptive use. FSRH, 2016. Available at: www.fsrh.org/ukmec/
Reproduced with permission
Intrauterine contraception (IUC) works via a local mechanism of action and there is no evidence of reduced effectiveness of levonorgestrel intrauterine systems (LNG-IUS) or copper intrauterine devices (Cu-IUD) in women with raised BMI.4 There are no studies looking at the safety of IUC based on weight or BMI, but there are no theoretical reasons why it should not be safe to use; IUC methods are UKMEC 1 in women with raised BMI.5 Although BMI alone does not restrict use of LNG-IUS, in combination with other cardiovascular risk factors (e.g. smoking, diabetes, hypertension) it is considered UKMEC 2.5
show In the general population, there is no evidence that IUC use causes weight gain. Furthermore, studies of the general population show that LNG-IUS and Cu-IUD use are associated with a reduced risk of endometrial hyperplasia and cancer, conditions which are themselves associated with high BMI.4 In practice, insertion and removal procedures may be more challenging; however, raised BMI has not been shown to be a significant factor in insertion failures.
Practical considerations to help reduce the risk of procedure failure should include having access to a supportive gynaecology couch, a variety of speculum sizes, and a large blood pressure cuff.4
The etonogestrel (ENG) implant is a highly effective method of contraception, though no studies have been designed with the specific aim of assessing the impact of weight or BMI on its effectiveness. The manufacturer suggests that earlier replacement of the implant may be considered in heavier women as plasma levels of etonogestrel are inversely related to body weight and decrease with time after insertion.6 The manufacturer does not, however, specify a weight at which early removal should be considered or how early an implant should be removed.
Clinical outcomes data, on the other hand, do not show an association between high BMI and implant failure (which is extremely rare in women of all weight categories). Based on the existing evidence, the FSRH recommends that the implant is a highly effective method that can be used by all women for 3 years.4 BMI alone is not sufficient to restrict implant use; however, when elevated BMI is combined with other cardiovascular risk factors, implants are considered UKMEC 2.5
There is no evidence of a causal relationship between the implant and weight gain in the general population. The implant may also have the added benefit of reducing dysmenorrhoea.7
Practically, provided that implants are correctly sited subdermally at insertion, they should be no more difficult to remove in women with raised BMI even if considerable weight gain has occurred during use.4
Progestogen-only injectables (i.e. depot medroxyprogesterone acetate [DMPA]) are an effective method of contraception in women of all weight categories and contraceptive failure is no more common in women with raised BMI than those without.4 In terms of safety, raised BMI alone does not restrict the use of DMPA (UKMEC 1). However, when raised BMI is one of multiple risk factors for cardiovascular disease it becomes UKMEC 3.5 A small body of research has linked DMPA to an increased risk of venous thromboembolism (VTE), but more research is required before a causal relationship can be established or refuted.4 Clinicians should consider this potential added risk in women already at increased risk of VTE due to high BMI.
The evidence around weight gain and DMPA comes mainly from studies in adolescents and demonstrates an association between DMPA use and weight gain, which may be greater in women under 18 years old with BMI ≥30 kg/m2. In the general population, women who gained more than 5% of their baseline body weight in the first 6 months of DMPA use were more likely to experience continued weight gain.4
Additionally, DMPA can be an effective treatment for heavy menstrual bleeding (HMB), dysmenorrhoea, and pain related to endometriosis.8,9 If clinicians are concerned about reaching the muscle to administer DMPA in women with obesity, they can consider injecting intramuscular DMPA into the deltoid rather than the gluteus, using a longer needle, or using subcutaneous DMPA.4
There is limited evidence as to the effectiveness of the progestogen-only pill (POP) in women with raised BMI. What data are available suggest that the POP is effective in women with raised BMI, so double-dose POP for contraception is not indicated or recommended.4 Like most other progestogen-only contraceptives, POP is UKMEC 1 for obesity alone and UKMEC 2 when other cardiovascular risk factors are also present.5
In the general population, there is no evidence of weight gain with POP use.4 Use of the desogestrel pill may alleviate dysmenorrhoea.10
Combined Hormonal Contraception
Combined hormonal contraception (CHC) is generally contraindicated (UKMEC 3) for use by women with BMI ≥35 kg/m2 because of increased thrombotic risk. Evidence suggests that increased weight or BMI does not make the combined pill or vaginal ring less effective; however, these methods may be less forgiving if they are used incorrectly, as ovarian activity during the hormone-free interval could be greater in women with obesity.4 Limited evidence suggests that the combined patch is less effective in women weighing ≥90 kg; the FSRH recommends that women who weigh ≥90 kg consider additional precautions or use alternative contraception.4
Obesity and CHCare independent risk factors for VTE as well as other adverse cardiovascular outcomes (specifically myocardial infarction and stroke). CHC is therefore UKMEC 2 for use by women with BMI 30–34 kg/m2, and UKMEC 3 for those with a BMI ≥35 kg/m2 as the risks generally outweigh the benefits.5 The guideline recommends that women should be informed that:
- the risk of thrombosis increases with increased BMI and
- current CHC use is associated with increased risk of VTE, myocardial infarction and ischaemic stroke and
- the risks of CHC generally outweigh the benefits in women with BMI ≥35 kg/m2.
In the general population, there is no evidence that CHC causes weight gain. Non-contraceptive benefits of CHC include relief of dysmenorrhoea, HMB, and polycystic ovary syndrome-related symptoms as well as a reduction in the risk of ovarian, endometrial, and colorectal cancers.11
Barrier and Fertility Awareness Methods
No studies have looked specifically at barrier methods or fertility awareness methods (FAM) in women with raised weight or BMI, but there are no theoretical reasons why these methods would be less effective or less safe. However, if women are experiencing irregular menstrual cycles they should not rely on FAM; healthcare professionals should discuss how irregular bleeding patterns affect fertility awareness. For women who experience a large change in weight, it is advisable to check that their diaphragm still fits.4
The Cu-IUD is the most effective form of emergency contraception (EC) for all women and its effectiveness is not affected by weight or BMI.
Oral levonorgestrel EC (LNG-EC) may be less effective in women weighing >70 kg or with BMI >26 kg/m2 and oral ulipristal acetate EC (UPA-EC) may be less effective in women weighing >85 kg or with BMI >30 kg/m2.12 The guideline advises that if a Cu-IUD is not suitable or acceptable, UPA-EC should be considered, and if UPA-EC is not suitable either, women can be offered a double dose of LNG-EC if their BMI is >26 kg/m2 or their weight is >70 kg.
It is not known how effective the double dose of LNG-EC is or how its effectiveness compares with that of UPA-EC. A double dose of UPA-EC is not recommended for women of any body weight or BMI.4,12
Women with obesity undergoing laparoscopic sterilisation are at increased risk of surgical and anaesthetic complications and technical failure of the procedure. This does not appear to be the case for hysteroscopic tubal sterilisation, although the device for this procedure is no longer available in the UK.4
Contraception and Weight Management
Women who are overweight or obese may be considering pharmacological or surgical treatment, and the guideline includes advice on contraception in this population—particularly for those undergoing bariatric surgery.
Weight Loss Medication
Pharmacological treatments for obesity available in the UK include orlistat, naltrexone/bupropion, and liraglutide. There are no known drug interactions between these medications and hormonal contraception, and very limited evidence about how weight loss medications affect contraceptive effectiveness. However, side-effects like diarrhoea and vomiting could reduce the effectiveness of the POP, combined oral contraception, and oral EC.4
Weight Loss Surgery
Women undergoing bariatric surgery are generally advised to avoid pregnancy during the subsequent period of intensive weight loss (12–18 months post-surgery) and these women should therefore be advised to consider long-acting reversible methods, as these have the lowest failure rates.4,5
There is no evidence that effectiveness of non-oral methods of contraception is affected by bariatric surgery. There are theoretical implications for oral contraception (OC) effectiveness after bariatric surgery due to malabsorption and post-surgery limitations on eating, drinking, and pill taking; women should be advised that the effectiveness of OC, including oral EC, could be reduced by bariatric surgery and OC should be avoided in favour of non-oral methods of contraception.
Women attending for EC following bariatric surgery should be offered Cu-IUD if eligible. If Cu-IUD is not appropriate or is contraindicated, there is no evidence to guide whether UPA-EC or double-dose LNG-EC is the more effective oral alternative.4
There is also limited evidence about safety of contraception after bariatric surgery. Apart from CHC, all methods of contraception are considered safe (UKMEC 1) for use in women with a history of bariatric surgery regardless of their BMI.5 CHC is UKMEC 3 for women with a BMI ≥35 kg/m2 and is UKMEC 2 for those with a BMI of 30–34 kg/m2 because of increased thrombotic risk. DMPA and bariatric surgery are both associated with a reduction in bone mineral density, but the clinical significance of their combined effect is not known.4 Women undergoing bariatric surgery are unlikely to be on CHC as it is UKMEC 3 for BMI ≥35 kg/m2, but if they are, they should be advised to stop CHC and use an alternative method of contraception for at least 1 month before surgery to minimise risk of post-operative VTE.4
Approaching Weight Issues in a Contraception Consultation
A respectful, non-judgmental, and culturally sensitive approach should be adopted when discussing the topic of weight in a contraception consultation. It may be helpful to talk about weight issues in the third person, and patients should be offered support and signposted to appropriate resources.
When talking about weight, it is good practice to ask the patient’s permission to discuss the subject and to explain why it is relevant in the context of a contraception consultation, e.g. ‘We know that body weight can affect some of the contraceptive choices. Is it ok if I talk to you about your weight?’ A number of useful resources for practitioners to inform constructive consultations can be found in Box 1.
|Box 1: Resources for Practitioners|
The guideline highlights a number of resources that may be useful for practitioners supporting women who are overweight or women with obesity:
RCGP=Royal College of General Practitioners; PHE=Public Health England
Important considerations need to be taken into account when helping women who are overweight or obese to choose appropriate contraception. Some of these considerations relate directly to the woman having raised BMI, whereas others are indirect and relate to co-morbidities or other health issues where overweight and obesity are risk factors.
The FSRH guideline aims to support healthcare professionals to understand the effectiveness and safety of contraception options in women with raised BMI, in order to assist them in making informed choices. Healthcare professionals providing contraception care are also well placed to raise the topic of weight and signpost women to appropriate support.
Dr Annabel Forsythe
Specialty Registrar in Community Sexual and Reproductive Healthcare, Oxfordshire Sexual Health Services
Valerie Warner Findlay
Researcher, Faculty of Sexual & Reproductive Healthcare’s Clinical Effectiveness Unit
UKMEC=UK Medical Eligibility Criteria for Contraceptive Use; BMI=body mass index; DMPA=depot medroxyprogesterone acetate; ENG=etonogestrel; POP=progestogen-only pill; CHC=combined hormonal contraception; VTE=venous thromboembolism; Cu‑IUD=copper intrauterine device; EC=emergency contraception; OC=oral contraceptive.
|Implementation Actions for STPs and ICSs|
Written by Dr David Jenner, GP, Cullompton, Devon
The following implementation actions are designed to support STPs and ICSs with the challenges involved with implementing new guidance at a system level. Our aim is to help you consider how to deliver improvements to healthcare within the available resources.
STP=sustainability and transformation partnership; ICS=integrated care system; FSRH=Faculty of Sexual & Reproductive Healthcare; Cu-IUD= copper intrauterine device; EC=emergency contraception