Weight-Loss Injections and Pregnancy: Do They Really Help You Get Pregnant?
Key Takeaways
Weight loss with a GLP-1 medicine may help ovulation return in some women with PMOS (PCOS). These are not fertility treatments, and more live births after IVF have not been proved. Before trying for a baby, stop semaglutide at least two months ahead and tirzepatide at least one month ahead.
Key evidence: International PCOS guideline (2023) EMA, Wegovy (semaglutide) summary of product characteristics EMA, Mounjaro (tirzepatide) summary of product characteristics
Weight-Loss Injections and Pregnancy: Do They Really Help You Get Pregnant?
It is 1.30 in the morning and your thumb is scrolling. In the first video, someone holds up an injector pen: “One shot, zero appetite.” In the next one: “I used this pen and, surprise, I got pregnant.” Between the two, a single flick of the thumb. You could almost conclude that you inject, then give birth.
Proving a scientific link takes a little more work than a swipe. GLP-1 medicines can contribute indirectly to the chance of pregnancy in some women. But they are not fertility treatments, and they are not used during pregnancy.
Here is what the studies show, when to stop treatment, and what to watch for if you plan a pregnancy or IVF.
Which medicines are we talking about?
GLP-1 is a hormone the gut releases after meals. It helps control blood sugar and tells the brain you are full.
Several medicines copy its action. Semaglutide is sold under names such as Ozempic and Wegovy; liraglutide belongs to the same family. Tirzepatide (Mounjaro) acts on the GLP-1 receptor and also on the receptor of a second hormone, GIP.[1][2]
Depending on the product, they are prescribed for type 2 diabetes, for weight management in people who meet the criteria, or for both. Most are injected once a week, hence the nickname “weight-loss pen”.
These medicines take time to leave the body. Their half-life is about one week for semaglutide and five days for tirzepatide. Half-life is the time it takes for the amount in the body to fall by half. Both can remain in the body for weeks after the last injection.[1][2]
How can weight loss bring ovulation back?
The main link is PMOS, previously called PCOS. In some women with the condition, insulin resistance and ovulation problems go together. The body responds poorly to insulin, and this keeps the hormone imbalance going. In some of these women, weight loss can help cycles become more regular and ovulation return.[3]
Beware of the shortcut. Not every woman with PMOS is overweight, and not every woman who is overweight has an ovulation problem. A PMOS diagnosis does not mean you need this medicine.
What do the studies show?
A meta-analysis pools results from earlier studies. A 2023 analysis found more regular cycles and more natural pregnancies in women with PCOS and overweight or obesity. The medicines studied were exenatide and liraglutide; these results do not establish a fertility benefit for semaglutide or tirzepatide. There was no clear difference in IVF pregnancies.[4]
A 2026 analysis was more cautious: it found modest short-term weight loss, while effects on reproduction remained uncertain because the data were weak.[5]
A 2026 registry study followed women with infertility and excess weight. Those who had taken semaglutide before fertility care had fewer pregnancies and fewer live births (pregnancies ending in a baby born alive).[6] This was an observational study: it watched what happened without assigning treatment, so it cannot prove the medicine was the cause. Treatment timing, or a deliberate delay in trying to conceive, may have shaped the results.
It also helps to separate the steps. Regular cycles, ovulation, a positive pregnancy test and the birth of a baby are four different outcomes. A pregnancy story on social media does not show that egg quality improved: it is coffee-machine talk, not scientific data.
Evidence box: studies on female fertility
- 2023 meta-analysis: 11 randomised trials, 840 women with PCOS and overweight or obesity. Four studies reported pregnancy rates. Exenatide or liraglutide was linked to more spontaneous pregnancies (relative risk 1.72) and more regular cycles. No significant difference for IVF pregnancies. Trials were often small and used different medicines, durations and add-on treatments such as metformin.[4]
- 2026 meta-analysis: 11 randomised trials in women with PCOS and overweight or obesity. Modest short-term fall in BMI; not enough data to judge cycle regularity; effect on reproduction uncertain (low certainty).[5]
- 2026 TriNetX cohort: 1,936 women aged 20 to 40 with infertility and overweight or obesity, matched one to one. Semaglutide taken in the year before fertility care was linked to fewer pregnancies and live births; time-to-event results were not consistently significant, and miscarriage rates did not differ. Retrospective design, with no information on IVF protocols or the stopping date.[6]
A “relative risk” compares how often an event happens in two groups. A “randomised” trial assigns treatment by chance. A “retrospective” study looks back at records that already exist.
What about IVF?
There is no solid evidence that these medicines increase the chance of a live birth after IVF. Their role in treating weight or diabetes is a separate question.[3][5]
The 2023 international PCOS guideline draws this line clearly. These medicines can be considered for weight management in people who meet the criteria. Using them to improve fertility in PCOS, however, remains limited to research.[3]
Treatment choices should therefore rest on a medical indication, such as weight or diabetes. Sometimes infertility in PMOS comes only from a lack of ovulation, with no other cause found. In that case, the first treatment recommended to trigger ovulation is letrozole.[3] To see when IVF becomes an option, read our article on IVF for women with ovulation disorders.
Why is contraception still essential?
Infrequent periods do not rule out pregnancy. Ovulation comes before a period, so you can conceive before regular periods return.
Human data are not enough to say these medicines are safe in pregnancy, and animal studies have shown harmful effects on reproduction, as the product information for semaglutide and tirzepatide states.[1][2] Effective contraception is therefore needed during treatment, as the PCOS guideline also stresses, and throughout the stopping period for each medicine.[3][7]
How long before a pregnancy should you stop?
The minimum stopping time depends on the medicine. The times below come from the European product information for semaglutide and tirzepatide.[1][2]
| Medicine (example brands) | Stop before a planned pregnancy |
|---|---|
| Semaglutide (Ozempic, Wegovy) | At least 2 months[1] |
| Tirzepatide (Mounjaro) | At least 1 month[2] |
| Other medicines in the family | Check the time for your product with your prescriber.[7] |
Agree with your prescriber which medicine you use, the date of your last injection and when you will start trying.
If you have diabetes, do not stop treatment on your own. Your team plans the switch to a blood sugar treatment suitable for pregnancy. This often takes several months, so you can start trying with blood sugar under control.[8]
Tirzepatide and the contraceptive pill
With tirzepatide, the pill may be absorbed less well because the medicine slows stomach emptying. UK advice is specific for women with overweight or obesity who take the pill.[7][9] For four weeks after starting treatment, and after each dose increase, they are advised:
- either to add a barrier method, such as condoms;
- or to switch to a non-oral method of contraception.
The EU product information gives different advice. In the version we checked on 17 October 2026, it says the fall in pill hormone exposure after a single dose is not clinically relevant and no pill dose adjustment is needed. It still recommends contraception during treatment.[2] If you take the pill, ask your doctor at the time of prescription which rule applies to you.
This warning does not apply in the same way to every GLP-1 medicine.[7]
Positive pregnancy test during treatment: what now?
Contact your prescriber and your gynaecologist straight away. The product information for both semaglutide and tirzepatide says to stop the medicine if pregnancy occurs.[1][2]
Being exposed to the medicine does not mean the baby has been harmed. A European study followed 168 pregnancies exposed in the first trimester. Major birth defects were not more common than in the comparison groups, but the study was too small to be sure.[10] A 2026 review found no clear safety signal, while stressing that the data are still not enough to rule out a risk.[11]
Your team will look at which medicine you used, the dose and the stage of pregnancy at exposure. If you have diabetes, another glucose treatment is started without delay: you should not be left untreated.[8]
Before IVF: weight is not a pass mark
Before IVF, age, ovarian reserve, the cause of infertility and the cost of waiting are weighed together. Telling every patient “lose weight first, then we’ll see” is not fair.
For some people, improving metabolic health before IVF makes sense. For others, a long delay may reduce the chance of a baby, especially as age advances.[12] Your weight is not a grade on a school report that decides whether you deserve treatment.
Egg collection and anaesthesia
If egg collection is planned, tell the IVF team and the anaesthetist about your treatment, even if it is “just a pen”.
These medicines slow stomach emptying. Even after the usual fasting, food may remain in the stomach and enter the lungs during deep sedation or general anaesthesia.[13]
The stopping time before pregnancy and the instructions before anaesthesia are two separate things. Follow the plan your team draws up for you, and do not change your treatment on your own. For the rest of the preparation, see our article on sedation or general anaesthesia for egg collection.
And men?
Obesity can also affect male fertility. In a study of men with obesity, sperm concentration and count rose after everyone followed a low-calorie diet. Men were then assigned by chance to different ways of keeping the weight off, including exercise and liraglutide. The gains lasted in those who maintained the weight loss.[14]
However, a 2026 systematic review found too little data on medicines, and few studies looked at whether pregnancies followed.[15] These medicines are not a proven treatment for male infertility. For other factors that may affect sperm, see our article on improving sperm quality.
Side effects and weight regain
Nausea, vomiting and digestive upset are the most common side effects. With tirzepatide, they are more frequent while the dose is being increased, then ease.[1][2]
After stopping, weight often comes back. In the STEP 1 trial extension, the semaglutide group regained about two-thirds of its lost weight over the following year.[16] Both the medicine and the structured lifestyle programme had been stopped. This was an exploratory analysis of a subset of adults without diabetes; it does not predict how much weight one person will regain.
That is why diet, physical activity, metabolic follow-up and the move towards pregnancy are best planned together, before stopping.
Three questions to ask your doctor
- Why do I medically need this medicine?
- When should I stop it before trying for a baby, and which contraception should I use until then?
- How does this change the timing of my fertility treatment?
Frequently Asked Questions for Dr. Aksoy
Can I keep taking Ozempic or Mounjaro during IVF?
We need to separate three stages.
During ovarian stimulation, there is no strong evidence that these medicines must be stopped. But data on how they affect egg quality, embryo development and IVF success when used during stimulation are also very limited. That is why, when I plan treatment, I prefer to stop them beforehand.
Egg collection raises a different issue. Ozempic and Mounjaro can slow stomach emptying. Even if a patient has fasted for the advised time, there may still be food in her stomach, which can raise the risk of aspiration under sedation or anaesthesia.
In the past, stopping these medicines one week before anaesthesia was recommended. Current anaesthesia guidance no longer recommends stopping them automatically for everyone. The dose, any nausea or vomiting and the anaesthesia setting are assessed together. When needed, precautions are taken, such as a liquid-only diet for 24 hours before the procedure.[17]
For embryo transfer, our approach is clearer. Women planning a pregnancy need to stop these medicines in advance:
- Ozempic (semaglutide): at least 2 months before the planned pregnancy;
- Mounjaro (tirzepatide): at least 1 month before the planned pregnancy.
These are the times given in the current European Medicines Agency product information.[1][2]
If we are freezing embryos, for example, we can plan egg collection and transfer at different times. But if we are considering a fresh embryo transfer, the stopping time has to be built in before treatment starts.
In short, during stimulation and egg collection the decision can be more individual; but at embryo transfer, when the goal is a pregnancy, I do not recommend using these medicines.
Should a man on Ozempic or Mounjaro stop before trying to conceive?
Based on what we know today, no. No recommendation requires men to stop Ozempic or Mounjaro before trying for a child. The one- or two-month waiting times set for women do not apply to men.
In fact, in men with overweight or type 2 diabetes, weight loss and better metabolic health can have positive effects on testosterone levels and some sperm parameters.[15][18]
We do need to be careful, though. We do not yet know how much of this benefit comes from the medicines themselves and how much from the weight loss. There are also not enough studies, particularly for Mounjaro, on sperm DNA integrity, pregnancy and live birth.
My approach is this: if a man uses the medicine for diabetes or obesity and is benefiting from it, I do not advise him to stop only because he wants a child. Of course, if the semen analysis is clearly abnormal, or if there is rapid weight loss or poor nutrition, we look at the situation again.
In short, there is no evidence that men need to delay their plans for a child because they take these medicines.
Can I restart a weight-loss injection after giving birth or while breastfeeding?
After birth, yes, treatment can be restarted. But if you are breastfeeding, there is an important difference between Ozempic and Mounjaro, and our knowledge has changed in recent years.
For Ozempic (semaglutide), the current European product information still advises against use while breastfeeding.[1] Yet in a small study published in 2024, no semaglutide was found in the milk of eight mothers using the injections. According to the mothers, the babies were developing normally; one mother noticed brief diarrhoea and reduced appetite in her baby while she herself had digestive side effects, with no clear effect on the baby’s weight or growth.[19] These data are encouraging, but they are not enough, especially for newborns and exclusively breastfed babies.
For Mounjaro (tirzepatide), there is a newer and important development. The European Medicines Agency product information, updated in January 2026, states that tirzepatide could be considered during breastfeeding.[2] In one study, 11 breastfeeding women received a single 5 mg dose of tirzepatide: the medicine was not detected in 164 of the 171 milk samples, and the amounts in the others were extremely low.[20] We still lack data on the effects of regular, long-term use on babies.
So it is no longer right to treat Mounjaro as strictly forbidden during breastfeeding. But for a mother who would use it only to lose weight, the decision should take into account the baby’s age, how she is breastfeeding and her own nutrition. Personally, for a mother who only wants to lose weight, and especially one breastfeeding a newborn, I prefer to postpone treatment. If there is a stronger medical reason, such as diabetes, I weigh the benefits and risks case by case.
Another important point is that these medicines can markedly reduce appetite. A breastfeeding mother needs enough energy, protein and fluids. So the question is not only whether the medicine passes into milk, but also how the mother’s nutrition may affect milk production and content.
In summary: if breastfeeding has ended and it is medically appropriate, treatment can be restarted. During breastfeeding, the official advice for Ozempic is still not to use it; Mounjaro can, on current data, be considered in selected patients.
Sources
- European Medicines Agency (EMA). Wegovy and Ozempic (semaglutide): summaries of product characteristics, sections 4.6 and 5.2. Accessed 17 October 2026. EMA, Wegovy · EMA, Ozempic
- European Medicines Agency (EMA). Mounjaro (tirzepatide): summary of product characteristics, sections 4.5, 4.6 and 5.2. Accessed 17 October 2026. EMA, Mounjaro · EMA, Mounjaro procedural steps (breastfeeding: EMA/VR/0000271898, January 2026)
- Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2023;108(10):2447–2469 (sections 4.5, 5.3.1, 5.9.1). PubMed · doi:10.1210/clinem/dgad463
- Zhou L, et al. Effects of GLP1RAs on pregnancy rate and menstrual cyclicity in women with polycystic ovary syndrome: a meta-analysis and systematic review. BMC Endocr Disord. 2023;23:245. PubMed · doi:10.1186/s12902-023-01500-5
- Forslund M, et al. GLP-1 receptor agonist treatment in women with polycystic ovary syndrome: a systematic review and meta-analysis. Eur J Endocrinol. 2026;194(3):25–39. PubMed · doi:10.1093/ejendo/lvag033
- Wu YC, et al. Impact of semaglutide pretreatment on reproductive outcomes in women with overweight and obesity with infertility: a real-world multicenter cohort study. Reprod Biol Endocrinol. 2026;24. PubMed · doi:10.1186/s12958-026-01549-6
- MHRA (UK). GLP-1 medicines for weight loss and diabetes: what you need to know. MHRA, GLP-1 guide
- American Diabetes Association. 15. Management of Diabetes in Pregnancy: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S321–S338. PubMed · doi:10.2337/dc26-S015
- Mounjaro (tirzepatide): UK summary of product characteristics, sections 4.5–4.6. emc
- Dao K, et al. Use of GLP1 receptor agonists in early pregnancy and reproductive safety: a multicentre, observational, prospective cohort study based on the databases of six Teratology Information Services. BMJ Open. 2024;14(4):e083550. PubMed · doi:10.1136/bmjopen-2023-083550
- Lau KGY, et al. Glucagon-like peptide-1 receptor agonists in pregnancy: periconception exposure and perinatal outcomes. BJOG. 2026. PubMed · doi:10.1111/1471-0528.70339
- Practice Committee of the American Society for Reproductive Medicine. Obesity and reproduction: a committee opinion. 2021. ASRM
- MHRA. GLP-1 and dual GIP/GLP-1 receptor agonists: potential risk of pulmonary aspiration during general anaesthesia or deep sedation. Drug Safety Update (January 2025). MHRA, Drug Safety Update 2025
- Andersen E, et al. Sperm count is increased by diet-induced weight loss and maintained by exercise or GLP-1 analogue treatment: a randomized controlled trial. Hum Reprod. 2022;37(7):1414–1422. PubMed · doi:10.1093/humrep/deac096
- Peel A, et al. The effect of obesity interventions on male fertility: a systematic review and meta-analysis. Hum Reprod Update. 2026;32(2):154–180. PubMed · doi:10.1093/humupd/dmaf025
- Wilding JPH, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes Obes Metab. 2022;24(8):1553–1564. PubMed · doi:10.1111/dom.14725
- Kindel TL, Wang AY, Wadhwa A, et al. Multi-society clinical practice guidance for the safe use of glucagon-like peptide-1 receptor agonists in the perioperative period. Surg Endosc. 2025;39(1):180–183. PubMed · doi:10.1007/s00464-024-11263-2
- Salvio G, et al. Effects of glucagon-like peptide 1 receptor agonists on testicular dysfunction: a systematic review and meta-analysis. Andrology. 2025;13(8):2022–2034. PubMed · doi:10.1111/andr.70022
- Diab H, et al. Subcutaneous semaglutide during breastfeeding: infant safety regarding drug transfer into human milk. Nutrients. 2024;16(17):2886. PubMed · doi:10.3390/nu16172886
- Eli Lilly. Mounjaro (tirzepatide): US prescribing information, section 8.2 Lactation (revised 08/2026). Lilly, Mounjaro US prescribing information
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