Contraception and weight

Weight is an important factor, as well as a medical issue, when it comes to choosing contraception!

Our patients may:

Worry about the impact of contraception on their weight, and misconceptions may deter patients from using effective methods.
Stop their contraception due to coincidental weight gain.

As healthcare professionals, we should consider:

The impact of weight on a patient’s risk of adverse medical events with certain contraceptive methods.
The importance of effective contraception for those living with obesity or underweight to prevent an unplanned pregnancy with increased risk of complications.
Counselling about the different methods of contraception and the importance of maintaining a healthy weight.

The FSRH has published numerous guidance documents regarding weight and contraception, including contraceptive options for women with eating disorders (FSRH CEU Statement: Contraception and weight gain, 2019; FSRH CEU Statement for women with eating disorders, 2018; FSRH 2019, Overweight, obesity and contraception).

The main points of these guidelines are summarised below.

This article was updated in June 2025.

Weight gain with contraception

In our discussions, we should consider that:

Weight gain is rarely a primary outcome in contraception studies.
There is a lack of consensus on what constitutes excessive or ‘unacceptable’ weight gain.
Weight gain can be a normal characteristic of growing older – especially in adolescence.
There may be other lifestyle and confounding factors.

This makes it difficult to determine the exact relationship between hormonal contraception and weight gain.

Considerations when prescribing contraceptives for those living with overweight or obesity

There is limited safety data regarding contraceptive use in obesity, particularly if BMI ≥40 or when combined with other comorbidities. However, those living with obesity are already at increased risk of cardiovascular disease and cancer (especially endometrial and breast), so caution may be needed.

Baseline risk of VTE in those living with obesity is two-fold higher than in women whose weight is in the healthy range.

Risks

Combined hormonal contraception increases the risk of CVD, VTE, and breast and cervical cancer.
Progestogen-only methods, including intrauterine systems, implants, pills and injections, may also increase the risk of breast cancer slightly.
A small amount of observational data has found an increased rate of VTE among progestogen-only injectable users. More research is needed before a causal association can be confirmed.

Benefits

Combined hormonal contraception reduces the risk of endometrial, ovarian and colorectal cancer.
The LNG-IUS is associated with a reduced risk of endometrial cancer. A BJGP umbrella review, including systematic reviews and meta-analyses, found that ever-use of any IUS was associated with reduced risk of endometrial cancer (and cervical and ovarian cancer). It also found 2 studies suggesting a possible but not statistically significant increased risk of breast cancer (British Journal of General Practice 2025; 75 (suppl 1): bjgp25X742329).
Limited evidence indicates no association between non-IUS progestogen-only contraception and endometrial or ovarian cancer.

Different methods of contraception and weight

The following table shows the relationship between the different contraceptive methods and weight.

NOTE: UKMEC categories: 1 is no restriction to use, 2 is benefits usually outweigh risks, 3 is risks usually outweigh benefits (relative contraindication), 4 is absolute contraindication (obesity is not a UKMEC 4 for any method of contraception!).

Contraceptive method	Does this method cause weight gain?	Does overweight or obesity impair this method of contraception?	UKMEC (i.e. safety of method) with obesity (BMI ≥30)
Intrauterine contraception (IUC)	No.	No: IUC is highly-effective contraception in women of all BMIs.	UKMEC 1. UKMEC 2 for IUS if obese and has another risk factor for CVD (smoking, hypertension, diabetes, dyslipidaemias).
Subdermal implant (SDI)	No.	No.	UKMEC 1. UKMEC 2 if has another risk factor for CVD.
Progestogen-only injectable (depot)	Depot may be associated with weight gain, especially in adolescents with a high BMI.	No evidence of reduction in efficacy (although data is limited if BMI >40). In obese women, the FSRH recommends: Longer needle or deltoid injection to ensure intra-muscular placement for Depo-Provera. Consideration of subcutaneous formulation.	UKMEC 1. UKMEC 3 if has another risk factor for CVD.
Progestogen-only pill (POP)	No.	No: do NOT increase the dose in obesity.	UKMEC 1. UKMEC 2 if has another risk factor for CVD.
Combined hormonal contraception (CHC)	No.	No: EXCEPT the efficacy of the combined patch may be reduced in women >90kg – so avoid.	UKMEC 2 if BMI ≥30–34. UKMEC 3 if has another risk factor for CVD. UKMEC 3 if BMI ≥35.

Emergency contraception: weight considerations

The copper IUD is the most effective emergency contraceptive method and is unaffected by weight.
The efficacy of oral emergency contraception may be reduced by being overweight (particularly levonorgestrel 1.5mg).
In those with a BMI >26 who request oral emergency contraception:
- Offer ulipristal acetate 30mg (EllaOne) first line.
- If not suitable, offer 3mg (double-dose) levonorgestrel.

Contraception, pregnancy and weight management treatments

Weight-loss medication

In June 2025, the MHRA released guidance on planning pregnancy for women using GLP-1 agonists (MHRA alert June 2025):

GLP-1 medications should be avoided during pregnancy due to lack of safety data.
The MHRA recommends a ‘washout period’ after stopping these medications before trying to conceive:
- Semaglutide: stop at least 2m before pregnancy.
- Tirzepatide: stop at least 1m before pregnancy.
- Liraglutide: no wash-out period is required.

Some weight loss medications may reduce efficacy of hormonal contraception.

Drug	Contraceptive	FSRH guidance and why
Any drugs which induce severe vomiting/diarrhoea
e.g. orlistat	COC POP	Follow missed pill rules if vomiting occurs within <3h of taking pill or severe diarrhoea occurs for >24h. If persistent diarrhoea or vomiting, consider non-oral method. Recommend consistent use of condoms.
		Why? May reduce absorption in the small intestine.
GLP-1 agonists
Tirzepatide (GLP-1 + GIP)	CHC POP	Remember MHRA advice: In those wanting to conceive, stop tirzepatide and allow at least 1 month ‘washout period’ before trying to conceive (MHRA alert June 2025). FSRH advice: In women on oral hormonal contraception, use additional barrier contraception for 4 weeks after starting tirzepatide, and for 4 weeks after any dose increase. Consider switching to a non-oral method of contraception while using tirzepatide. Emergency contraception: there is no direct evidence of the impact of tirzepatide on emergency hormonal contraception. The copper IUD should be offered where appropriate. In women with a BMI >26 or weight >70kg, consider double-dose LNG-EC if this is the patient’s preferred method.
		Why? Tirzepatide has been found in clinical trial data to have a clinically significant effect on the bioavailability of oral contraceptives (CEU-statement-GLP-1-agonists-and-contraception.pdf).
Other GLP-1 drugs	No contraceptive limitations	Remember MHRA advice: In those wanting to conceive, stop semaglutide and allow at least 2 months ‘washout period’ before trying to conceive (MHRA alert June 2025). FSRH advice: There is no need to add a barrier method of contraception when using semaglutide, dulaglutide, exenatide, lixisenatide or liraglutide. Follow usual guidance if severe vomiting or diarrhoea occur as a side-effect of these medications.
		Why? There is currently no evidence that semaglutide, exenatide, liraglutide, dulaglutide or lixisenatide reduce the effectiveness of oral contraception.

Weight-loss surgery

Bariatric surgery and fertility

Those living with obesity are at increased risk of infertility; undergoing bariatric surgery improves fertility (as well as maternal outcomes).
Due to accelerated weight loss and changes in digestive physiology post-surgery, women should avoid pregnancy for 12–18m.

Bariatric surgery and contraception

There is little evidence examining the efficacy of different contraceptive methods in women who have undergone bariatric procedures.
Oral contraception may be less effective post-operatively so non-oral contraception should be considered.
All those using CHC should stop at least 4w prior to major surgery.

Eating disorders and contraception

We should be alert to the possibility of an eating disorder in those with oligo/amenorrhoea. The FSRH makes the following points regarding eating disorders and contraception:

Issues	Advice
The importance of contraception usage	Eating disorders can cause irregular menstrual cycles or amenorrhoea, particularly in those with low BMIs, and some women may interpret this as a sign of subfertility. However, ovulation is unpredictable so effective contraception is vital. Pregnancies in those who are underweight are associated with hyperemesis, anaemia, IUGR and prematurity.
Fears about weight gain	We can reassure patients that there is no conclusive evidence that hormonal contraception causes weight gain. There is some evidence that the progestogen-only injectable is associated with weight gain in women without eating disorders. Hormonal contraception may be associated with body changes (e.g. bloating, breast enlargement) which may be unacceptable to some (non-hormonal options may be better).
Bone mineral density concerns	>90% of women with anorexia have osteopenic bones, and women with bulimia also demonstrate lower bone mineral densities. The mechanism for bone loss in women with eating disorders appears to be multifactorial, and not just a result of low body weight and oestrogen levels. Nutritional and growth factors may also be implicated. Evidence suggests that oestrogen treatment in the form of CHC alone does NOT increase bone mineral density in women with anorexia. There is no evidence looking at the effect of progestogen-only injectables on bone mineral density in women with anorexia. However, as anorexia is a significant risk factor for osteoporosis, the use of depot should be carefully discussed and used with caution.
Vomiting and laxative misuse	The absorption of oral contraception may be impaired in those who practice self-induced vomiting or who overuse laxatives, although there is limited evidence examining the impact on oral contraceptive efficacy. In women who choose oral contraception, we should advise extra precautions if: Vomiting occurs within 3h of pill-taking. They have diarrhoea for >24h. LARC methods may be more effective.
Long-acting reversible contraception (LARC)	LARC methods are highly effective and user-independent, and should be considered first-line contraceptive options, particularly in those with eating disorders for whom birth outcomes may be poor. Subdermal implants: Underweight women may have little subcutaneous tissue so we should be careful to avoid deep implant insertion. Intrauterine contraception (IUC): Amenorrhoeic women with eating disorders may have an atrophic uterus with a short uterine cavity, so a smaller intrauterine device may be more suitable. We should be aware that patients may not have eaten prior to attending for a procedure so may be at greater risk of a vaso-vagal reaction (but this is not a contraindication to fitting!). Those with anorexia are also at increased risk of developing bradycardia, low blood pressure and prolonged QT interval (prolonged QT interval is a UKMEC3 for initiation of IUC – liaise with cardiology prior to fitting).
Vaginal health	Hypoestrogenic women with anorexia may experience vaginal dryness and dyspareunia. We should suggest using a lubricant to alleviate symptoms during sex, and could consider topical oestrogens.

Contraception and weight

There is limited evidence looking at the effect of contraception on weight.

Progestogen-only injectables are the ONLY method of contraception that has been associated with weight gain – especially in overweight adolescents.

There is no evidence that obesity affects the efficacy of any method of contraception EXCEPT the combined patch in women over 90kg.

Obesity alone does not restrict the use of any method of contraception, but more caution is required with combined hormonal contraception.

Those with eating disorders may be fertile and need effective contraception even if they are oligo or amenorrhoeic.

Birth outcomes are worse in underweight women, and LARC methods are the most effective methods of contraception.

Combined hormonal contraception does not provide bone protection in women with anorexia.

Avoid oral contraception in women who have undergone malabsorptive bariatric procedures.

Ever-use of IUS is associated with reduced risk of endometrial cancer, for which obesity is a known risk factor.