Overweight, Obesity, and Contraception

Faculty of Sexual and Reproductive Healthcare

Overview

This Guidelines summary focuses on contraceptive choices for women who are overweight and women with obesity, and other potential considerations relating to contraception in women with raised body mass index (BMI), such as contraception after bariatric surgery and during use of weight-loss medication.

Recommendations include:

method-by-method effectiveness, safety, effect on weight, and health benefits
contraception and weight management treatment
approach to issues of weight in contraceptive consultations.

For more information on the available evidence and data, suitability of contraceptive methods for women who are overweight or obese, and recommendations for future research, refer to the full guideline.

Grading of Recommendations

For a full explanation of the classification of evidence level and grading of recommendations, refer to Appendix 1 in the full guideline.

A: at least one meta-analysis, systematic review, or randomised controlled trial (RCT) rated as 1++, and directly applicable to the target population; or a systematic review of RCTs or a body of evidence consisting principally of studies rated as 1+, directly applicable to the target population and demonstrating overall consistency of results.

B: a body of evidence including studies rated as 2++ directly applicable to the target population and demonstrating overall consistency of results; or extrapolated evidence from studies rated as 1++ or 1+.

C: a body of evidence including studies rated as 2+ directly applicable to the target population and demonstrating overall consistency of results; or extrapolated evidence from studies rated as 2++.

D: evidence level 3 or 4; or extrapolated evidence from studies rated as 2+.

[✓]: good practice point based on the clinical experience of the guideline development group (GDG).

Reflecting on Your Learnings

Reflection is important for continuous learning and development, and a critical part of the revalidation process for UK healthcare professionals. Click here to access the Guidelines Reflection Record.

Method-by-method Effectiveness, Safety, Effect on Weight, and Health Benefits

Intrauterine Contraception

[C] Intrauterine contraception (IUC) is a highly effective method of contraception and available evidence suggests that its effectiveness is not affected by body weight or BMI.

[D] The available evidence suggests that IUC is a safe contraceptive option for women who are overweight and women with obesity.

There are limited data relating to IUC use by women with raised BMI. For more information on effectiveness, safety, weight gain, and benefits in the general population, refer to the FSRH guideline Intrauterine contraception.

IUC Effectiveness

The mechanisms of action of IUC are based on local effects and do not rely on systemic drug levels; a woman’s weight would not be expected to affect contraceptive effectiveness of the copper intrauterine device (Cu-IUD) or levonorgestrel-releasing intrauterine system (LNG-IUS)
There is no evidence of impaired contraceptive effectiveness in IUC users with obesity, either with the Cu-IUD or the LNG-IUS.

IUC Safety

Cu-IUD

No studies have specifically evaluated the safety of the Cu-IUD in women with raised BMI. There are no theoretical reasons why the Cu-IUD would pose health risks to women with raised BMI
According to the UKMEC, obesity does not restrict the use of the Cu-IUD (UKMEC 1).

LNG-IUS

According to the UKMEC, obesity alone does not restrict the use of the LNG-IUS (UKMEC 1). Even when obesity is in the context of other risk factors for cardiovascular disease (CVD) (for example, smoking, diabetes, and hypertension), use of the LNG-IUS is UKMEC 2.

Weight Gain With IUC

There is no specific evidence relating to weight gain with IUC use by women with raised BMI.

Health Benefits of IUC

Obesity is associated with increased risk of endometrial hyperplasia and cancer. Although not directly studied in women with obesity, studies of women in the general population suggest that use of the LNG-IUS or Cu-IUD is associated with reduced risk of endometrial hyperplasia and cancer. The mechanism by which the Cu-IUD could reduce endometrial cancer risk has not been defined.

Practical Considerations With IUC

IUC insertion for women with raised BMI is appropriate, safe, and feasible. IUC is a highly effective and safe contraceptive option for women who are overweight and women with obesity
In practice, IUC insertion may be more challenging in women with obesity than in normal-weight women in terms of assessment of uterine position and gaining access to the uterus; however, raised BMI is not a significant factor in failed IUC insertions or expulsions and insertion difficulties should not be presumed in women with raised BMI.

Progestogen-only Implants

[C] The etonogestrel (ENG) implant is a highly effective method of contraception and available evidence suggests that its effectiveness is not affected by body weight or BMI.

[✓] The licensed duration of ENG implant use of 3 years applies to women of all weight categories.

[C] The available evidence suggests that the ENG implant is a safe contraceptive option for women who are overweight and women with obesity.

The single-rod etonogestrel (ENG) implant (Nexplanon^®) is the only implant currently available in the UK, and is the method referred to as the ‘implant’ or ‘IMP’ throughout this guideline summary
There are limited data relating to IMP use in women who are overweight or women with obesity. For more information on implant effectiveness, safety, weight gain, and benefits in the general population, refer to the FSRH guideline, Progestogen-only implants.

Implant Effectiveness

The implant is a highly effective method of contraception, and true contraceptive failures are very rare (see Table 2 in the full guideline).

Implant Safety

According to the UKMEC, obesity alone does not restrict the use of IMP (UKMEC 1). Even when obesity coexists with other risk factors for CVD (for example, smoking, diabetes, and hypertension), use of IMP is UKMEC 2
No studies have directly assessed cardiovascular risk in women who are overweight or have obesity and use IMP.

Weight Gain With Implants

In the general population of all implant users, there is no evidence of a causal association between implant use and weight gain. There is no specific evidence relating to weight gain with IMP use by women who are overweight or women with obesity.

Health Benefits of Implants

The main non-contraceptive benefit of IMP is that it may help alleviate dysmenorrhoea and ovulatory pain that are not associated with any identifiable pathological condition
While there is theoretically no reason why this would not be the case for women who are overweight or with obesity, this has not been specifically studied in women of different weight categories.

Practical Considerations With Implants

There are no data to suggest placement or removal of IMP is problematic in women who are overweight or women with obesity
Correct subdermal placement of the implant is important in women of all BMIs
Insertion or removal difficulties should not be presumed in women with raised BMI. Removal of appropriately placed implants (for example, subdermal placement) should not be affected by BMI, including in the case of weight gain after insertion.

Progestogen-only Injectable

[C] The available evidence suggests that effectiveness of depot medroxyprogesterone acetate (DMPA) is not affected by body weight or BMI.

[B] From the limited evidence available it is not possible to confirm or exclude a causal association between DMPA use and venous thromboembolism (VTE).

[D] Whilst obesity alone does not restrict the use of DMPA (UKMEC 1), DMPA use becomes a UKMEC 3 when obesity is one of multiple risk factors for CVD (for example, smoking, diabetes, and hypertension).

[B] DMPA use appears to be associated with some weight gain, particularly in women under 18 years of age with BMI 30 kg/m² or greater.

[✓] For women with obesity:

if using intramuscular DMPA or norethisterone enanthate (NET-EN) injectable, consider use of a longer-length needle or deltoid administration to ensure the muscle layer is reached
consider use of subcutaneous DMPA.
Three progestogen-only injectable contraceptives are available in the UK: DMPA; intramuscular (DMPA-IM) and subcutaneous (DMPA-SC) progestogen-only injectables, which are administered every 13 weeks; and NET-EN injectable, which is administered every 8 weeks
There are limited data relating to progestogen-only injectable use in women who are overweight or women with obesity. For more information on effectiveness, safety, weight gain, and benefits in the general population, refer to the FSRH guideline, Progestogen-only injectable contraception.

DMPA Effectiveness

There is limited evidence regarding the effect of weight on the contraceptive effectiveness of progestogen-only injectable contraception, and no studies have specifically compared DMPA-IM or NET-EN failure rates in women with obesity versus women of normal weight
Overall, the available evidence indicates that the contraceptive effectiveness of DMPA is not affected by weight or BMI.

DMPA Safety

According to the UKMEC, obesity alone does not restrict the use of progestogen-only injectable contraception (UKMEC 1). However, when obesity is one of multiple risk factors for CVD (for example, smoking, diabetes, and hypertension), use of progestogen-only injectable contraception becomes a UKMEC 3 (the theoretical or proven risks usually outweigh the advantages of using the method)
The UKMEC notes that for women using NET-EN, the UKMEC categories are considered the same as for DMPA.

Weight Gain with DMPA

The data on progestogen-only injectable use and weight gain specifically in women who are overweight or women with obesity mainly derive from studies of adolescents
Overall, the available evidence indicates that use of DMPA is associated with some weight gain.

Health Benefits of DMPA

DMPA can be used as a treatment for the management of heavy menstrual bleeding (HMB), dysmenorrhea, and for pain associated with endometriosis
DMPA may confer some protection against ovarian and endometrial cancers
While there is no reason to expect this would not be the case for women with raised BMI, the health benefits associated with DMPA have not been specifically studied in women of different weight categories.

Practical Considerations With DMPA

The summary of product characteristics (SPC) for DMPA-IM states that it should be administered by deep intramuscular (IM) injection into muscle tissue, preferably the gluteus maximus, but other muscle such as the deltoid (upper arm) may be used. Traditionally the dorsogluteal site (upper outer quadrant of the buttock) has been used
The ventrogluteal site (lateral thigh) has been investigated as an alternative site because the risk of sciatic nerve injury is reduced and the fat layer is thinner than in the dorsogluteal area. However, in women who are classified as overweight or obese it may be difficult to ensure IM administration in either the dorsogluteal or ventrogluteal region
If there are concerns about the ability to administer an IM injection due to body weight then the deltoid muscle in the upper arm may be considered as an alternative site or DMPA-SC could be a suitable alternative.

Progestogen-only Pill

[D] The available evidence suggests that effectiveness of progestogen-only pill (POP) is not affected by body weight or BMI.

[D] The available evidence suggests that POP is a safe contraceptive option for women who are overweight and women with obesity.

[✓] Double-dose POP for contraception is not recommended for women who are overweight or women with obesity.

There are limited data relating to POP use in women with raised BMI. For more information on effectiveness, safety, weight gain, and benefits in the general population, refer to the FSRH guideline, Progestogen-only pills.

POP Effectiveness

There is very limited evidence on POP effectiveness in women who are overweight or women with obesity. The available data have not shown reduced POP effectiveness in women with higher weight and/or BMI
The SPCs for POPs do not advise dose adjustments based on weight or BMI.

POP Safety

According to the UKMEC, obesity alone does not restrict the use of POP (UKMEC 1 indicating no restrictions on use). Even when obesity is in the context of other risk factors for CVD (for example smoking, diabetes, and hypertension), use of POP is UKMEC 2.

Weight Gain With POP

In the general population there is no evidence suggesting a causal association between POP use and weight gain. There is no specific evidence relating to weight gain with POP use by women with raised BMI.

Health Benefits of POP

The main non-contraceptive benefits of POP are that they may help alleviate HMB and dysmenorrhoea, with possible alleviation of premenstrual syndrome symptoms for the desogestrel-containing POP. While there is theoretically no reason this would not be the case for women with raised BMI, this has not been specifically studied in women of different weight categories.

Combined Hormonal Contraception

[C] Most evidence suggests that effectiveness of combined oral contraception/contraceptive (COC) is not affected by body weight or BMI.

[D] Limited evidence suggests a possible reduction in patch effectiveness in women weighing 90 kg or greater.

[D] Limited evidence suggests that effectiveness of the vaginal ring is not affected by body weight or BMI.

[D] Combined hormonal contraception (CHC) use is UKMEC 2 for use by women with BMI 30–34 kg/m² or greater and UKMEC 3 for women with BMI 35kg/m² or greater.

[C] Women with obesity should be informed that:

risk of thrombosis increases with increasing BMI
current CHC use is associated with increased risk of VTE
current CHC use is associated with a small increased risk of myocardial infarction (MI) and ischaemic stroke
if BMI is 35 kg/m² or greater the risks associated with use of CHC generally outweigh the benefits.
Note that UKMEC recommendations relate to safety of use rather than to effectiveness of contraceptive methods
There are limited data relating to CHC use in women who are overweight or women with obesity. For more information on effectiveness, safety, weight gain, and benefits in the general population, refer to the FSRH guideline Combined hormonal contraception.

CHC Effectiveness

COC

The findings of studies of COC effectiveness in relation to increased body weight/BMI vary. In general, evidence relating to the effect of increased body weight/BMI on effectiveness of COC is limited to observational studies in which height, weight, and pregnancy are often self-reported, and potential confounding factors such as contraceptive adherence and frequency of sexual intercourse are unknown
There is limited evidence that ovarian activity in the hormone-free interval could be more pronounced in obese women.

Combined Transdermal Patch

The combined transdermal patch (also referred to as the patch) currently available in the UK, Evra®, is an ethinylestradiol (EE)/norelgestromin (NGMN) patch
Data on the patch in the context of obesity are limited. The limited evidence identified suggests that increasing body weight and BMI may be associated with increasing contraceptive failure rates of the EE/NGMN patch
The SPC for the Evra patch states that contraceptive effectiveness could be decreased in women weighing 90 kg or greater. As there are no new data to refute the manufacturer’s statement, the GDG recommends that additional precautions for pregnancy prevention or an alternative method of contraception should be advised for women weighing 90 kg or greater.

Combined Vaginal Ring

The combined vaginal ring (also referred to as the ring) contains EE and ENG
Data on the ring in the context of obesity are limited.

CHC Safety

UKMEC recommendations relate to safety of use. CHC is UKMEC 3 for use by women with BMI 35 kg/m² or greater. Use of CHC is UKMEC 2 for use by women with BMI 30–34 kg/m² or greater
These UKMEC 2 and 3 classifications, which indicate safety concerns for obese women using CHC, are related to cardiovascular risks from exogenous oestrogen, including VTE, acute MI, and stroke. They are based primarily on evidence that obesity and CHC use are both independent risk factors for thrombosis.

Venous Thromboembolism

Independent of CHC use, the risk of VTE rises as BMI increases over 30 kg/m² and rises further with BMI greater than 35 kg/m². Baseline VTE risk in obese women is two-fold higher than VTE risk in normal-weight women
VTE risk also increases significantly with age, irrespective of BMI
CHC is associated with an increased risk of VTE, with use of CHC increasing VTE risk three-fold (in non-obese CHC users)
Women with obesity should be advised about effective methods of contraception that are not associated with increased risk of VTE.

Weight Gain With CHC

In the general population there is no evidence that use of CHC causes weight gain. There is no specific evidence relating to weight gain with CHC use by women who are overweight or women with obesity.

Health Benefits of CHC

Many non-contraceptive benefits are associated with CHC, including reduction of HMB and pain, alleviation of premenstrual symptoms, and management of symptoms associated with polycystic ovary syndrome. There is also a reduced risk of endometrial, ovarian, and colorectal cancer.

Barrier Methods of Contraception

Barrier Method Effectiveness

No studies have evaluated the effectiveness of barrier methods in women with obesity versus women without obesity or assessed weight-related effectiveness
Following a large change in weight or childbirth, the GDG suggests good practice would be to check if a woman’s diaphragm still fits
Barrier methods are prone to user-related contraceptive failure due to non-adherence or incorrect use. This is reflected in their relatively higher contraceptive failure rates when compared to other contraceptive methods (see Table 2 in the full guideline).

Barrier Method Safety

No studies have specifically evaluated the safety of barrier methods of contraception in women with raised BMI.

Fertility Awareness Methods

There is no evidence relating to fertility awareness methods and BMI.

Emergency Contraception

[✓] The available evidence suggests that effectiveness of the Cu-IUD is not affected by body weight or BMI.

[C] 1.5 mg levonorgestrel emergency contraception (LNG-EC) appears to be less effective in women with BMI greater than 26 kg/m² or weight greater than 70 kg.

[C] Ulipristal acetate emergency contraception may be less effective in women with BMI greater than 30 kg/m² or weight greater than 85 kg.

[C] Women should be informed that the Cu-IUD is the most effective method of emergency contraception (EC).

[C] Women should be informed that BMI greater than 26 kg/m² or weight greater than 70 kg may reduce the effectiveness of oral EC, particularly of LNG-EC.

Contraception and Weight Management Treatment

Weight-loss Medication and Contraception

[✓] Women should be advised that it is possible that medications that induce diarrhoea and/or vomiting (for example, orlistat, laxatives) could reduce the effectiveness of POP, COC, and oral EC.

Weight-loss Surgery and Contraception

[C] Non-oral contraceptives have been studied in only small numbers of women following bariatric surgery but appear to be safe and effective.

[C] For women with BMI 35 kg/m²or greater, risks associated with CHC use generally outweigh the benefits.

[✓] Women receiving counselling regarding bariatric surgery should have a discussion about contraception and have a plan for contraception in place prior to surgery.

[D] 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.

[D] Women should be advised to stop CHC and to switch to an alternative effective contraceptive method at least 4 weeks prior to planned major surgery (for example, bariatric surgery) or an expected period of limited mobility.

Approach to Issues of Weight in Contraceptive Consultations

[✓] When providing contraception to women with raised BMI, healthcare professionals (HCPs), after asking permission, should raise the subject of weight, enquire about whether BMI is of concern, and signpost to appropriate support for weight management if wanted.

HCPs giving contraception care are well placed to raise the topic of weight and signpost women to appropriate support, because issues of weight are relevant to contraceptive decision-making. It is good practice to calculate and document BMI when providing contraception. Many HCPs feel concerned they may cause offense when discussing weight
The GDG suggests that safe principles include:
- ask permission to discuss weight
- use a respectful and non-judgemental approach
- give context as to why weight is relevant to your discussion
- be aware of stigmatising language
- be sensitive to cultural issues (different cultures value weight in different ways)
- use the ‘third person’ to convey factual information about risks to reduce chance of patients becoming defensive or feeling disempowered or burdened by their weight
- offer supportive resources and referrals for weight management if appropriate.
The following phrases could encourage a positive conversation when raising the topic of weight with contraception patients:
- ‘I would like to talk to you about your weight. Is that okay?’
- ‘How do you feel about your weight?’ or ‘Do you have any concerns about your weight? Is this something you would like more help with?’ HCPs should be aware of local weight management support services in their locality or signpost to web-based resources such as NHS Choices
- ‘We know that body weight can affect some of the contraceptive choices. Is it okay if I talk to you about your weight?’
- ‘We know that a higher BMI is linked to increased risk of…/may affect the safety of…/may alter the effectiveness of… shall I explain more about this risk?’

Practical Considerations

Facilities providing contraceptive care should have weighing scales that can accurately measure high body weights.