GLP-1 medications, such as Mounjaro and Wegovy, aren’t fertility drugs. However, they can help improve your chances of conceiving. They do this by addressing metabolic issues that affect normal hormonal function. These medicines are also commonly used as part of weight management treatment.
They must be stopped before planning a pregnancy. Also, anyone using oral contraceptives should know about a specific absorption risk. Most patients are never warned about this.
There is a lot of nuance here, and the sections below explain these considerations in detail.
Table of Contents
Do Weight Loss Injections Cause Infertility?
This is the first thing most people want to know, so let’s settle it directly. No, researchers have not shown that GLP-1 receptor agonists cause permanent infertility. The FDA and the UK’s MHRA do not list irreversible infertility as a side effect of semaglutide (Wegovy, Ozempic) or tirzepatide (Mounjaro).
Semaglutide is approved in the UK only for type 2 diabetes. There is no clinical evidence that these medications harm reproductive organs or affect fertility in men or women. This conclusion comes from both large trial data and post-market surveillance.
People mainly worry about timing and safety during pregnancy. They don’t fear that the drugs will harm their ability to conceive.
Can Weight Loss Improve Fertility?
Yes, and this is where things get genuinely interesting. Excess body fat disrupts the hormonal system in ways that directly impair fertility. It raises oestrogen and insulin levels. It also weakens ovulatory signals. This makes it harder for conception to happen.
Losing just 5 to 10% of body weight can help restore ovulation in some women who previously did not ovulate. This is the physiological explanation behind the “Ozempic babies” trend that made headlines over the past couple of years.
Some people who struggled to conceive for years became pregnant after starting GLP-1 therapy. This didn’t happen because the drug directly boosted fertility. Instead, it improved the metabolic issues that were in the way.
Weight loss injections can boost insulin sensitivity. They also reduce inflammation in the body. Plus, they help regulate reproductive hormones better. This may meaningfully improve fertility.
Weight Loss Injections and PCOS
Polycystic ovary syndrome (PCOS) is the leading cause of ovulatory infertility in the UK. It affects about 1 in 10 women of reproductive age. At its core, PCOS is a metabolic condition, not just a gynaecological one, and insulin resistance sits at the centre of it.
High insulin levels lead the ovaries to make too much androgen, like testosterone. This affects ovulation and causes the main symptoms of PCOS. GLP-1 medications target insulin resistance directly. By improving how the body handles glucose, they reduce androgen production and allow the menstrual cycle to regulate.
For women with PCOS who have not responded adequately to lifestyle changes alone, tirzepatide and semaglutide may offer a meaningful improvement in cycle regularity and ovulation frequency.
Neither medication is licensed in the UK for PCOS or for fertility treatment. Any benefit comes from weight loss, not from the medication’s intended use. It should not replace specialised care for PCOS. This should always be discussed with a specialist rather than treated as a standalone fertility solution.
Can Weight Loss Injections Affect Male Fertility?
Men are often left out of the fertility conversation, but obesity impairs male reproductive health in measurable ways. Excess body fat can lower testosterone and raise oestrogen levels. It also increases scrotal temperature. This leads to poorer sperm quality.
Clinical research shows that losing weight can boost sperm count, sperm motility, and sperm morphology. It also raises testosterone levels naturally. GLP-1 medications help with significant and lasting weight loss. This weight loss can lead to indirect improvements.
There is limited long-term data on GLP-1s and male reproductive health. However, the available information does not indicate any harm to sperm or testicular function. The overall effect of GLP-1 treatment in overweight men is expected to be positive rather than harmful.
Can Weight Loss Injections Make Birth Control Fail?
This applies specifically to Mounjaro. If you take the oral contraceptive pill, use condoms as well, or switch to a non-oral method such as the coil or implant for four weeks after you start and for four weeks after every dose increase.
Dose increases happen roughly monthly at first, so this comes up more than once. For Wegovy and other semaglutide treatments, the evidence doesn’t show a significant effect on the pill. However, severe vomiting or diarrhoea from these medicines can lower absorption like usual.
What to Do If You Get Pregnant on Weight Loss Injections
First, do not panic. Stop the injections immediately and contact your obstetrician or midwife as soon as possible.
Animal studies with GLP-1 medications found possible risks to foetuses at high doses. So, pregnancy is a contraindication. However, more recent human data on first-trimester exposure is reassuring.
Studies on accidental pregnancies while using semaglutide show no higher rate of major birth defects. This is similar to pregnancies managed with insulin in women with type 2 diabetes.
The key action is stopping the medication promptly. Do not wait until your next appointment. Inform your GP or a specialist so your pregnancy can be monitored appropriately from the start.
The UKTIS (UK Teratology Information Service) considers exposure before pregnancy to be low risk. They get reports on these exposures, which helps offer reassurance.
Weight Loss Injections and IVF
If you are planning IVF or any assisted conception, the timing of stopping your weight loss injections matters. The washout period differs by medication. The MHRA recommends stopping tirzepatide (Mounjaro) one month before trying to conceive. For semaglutide (Wegovy), stop at least two months ahead. Fertility clinics may ask you to wait longer before egg collection. This is partly for anaesthetic safety. So, check your clinic’s requirements.
One thing to start rather than stop: Anyone trying to conceive should take folic acid daily from before conception until 12 weeks. The usual dose is 400 micrograms, but if your BMI is 30 or above, the recommended dose is 5 mg, which needs a prescription. Sort this out when you plan your washout, not after.
There are two reasons for this. First, the drug needs to clear your system fully before the hormonal stimulation phase of IVF begins. Second, GLP-1s slow gastric emptying, which increases the risk of aspiration during the anaesthesia used for egg collection. Anaesthetists take that risk seriously. Most clinics won’t proceed until they confirm the medication has been stopped for long enough.
If you are on a weight loss injection and considering IVF, raise this with your fertility consultant at your first appointment. Do not wait until your treatment cycle begins to mention it.
Frequently Asked Questions
Does stopping Mounjaro quickly restore normal fertility?
Fertility-related hormonal changes typically begin to stabilise within a few weeks of stopping. For women who want to conceive, the standard advice is to have a two-month washout period before trying.
Can weight loss injections affect AMH levels or ovarian reserve?
There is currently no robust clinical evidence that semaglutide or tirzepatide affects anti-Mullerian hormone (AMH) levels or reduces ovarian reserve. Research in this area is still limited.
Are weight loss injections safe to use while breastfeeding?
Both Mounjaro and Wegovy are contraindicated during breastfeeding. We don’t know if these drugs go into breast milk in significant amounts, so they should not be used while breastfeeding.
Should I tell my fertility clinic I was on weight loss injections?
Yes, always. Your fertility specialist needs your complete medication history, even if you stopped months ago. This helps them plan your treatment safely and adjust the washout timeline if needed.
Can weight loss injections replace Metformin for PCOS-related infertility?
GLP-1s are not a licensed replacement for metformin in PCOS management. Some evidence shows they might work better for weight loss and insulin resistance. However, this is not standard first-line guidance yet. Speak to your GP or an endocrinologist for a personalised assessment.
Conclusion
Weight loss injections do not cause infertility. In many cases, they improve the underlying metabolic conditions that make conception difficult. But they have strict timing rules: stop before planning a pregnancy. Also, those using oral contraceptives should know about the absorption risk.
If you’re using Mounjaro or Wegovy and thinking about fertility, it’s important to talk to a pharmacist or GP first. This is crucial whether you’re trying to conceive, going through IVF, or just exploring your options.
At The Easy Pharmacy, our team helps you see how weight loss medications fit into your overall health. We can also refer you to the right specialist if needed.
Dilip Modhvadia is the Co-Founder and Superintendent Pharmacist at Easy Pharmacy, with over 20 years of experience in community pharmacy. He holds an MPharm and is registered with the GPhC (Reg. No. 2050606). He leads Easy Pharmacy’s clinical services, providing professional, patient-focused care.