Mounjaro® and Pregnancy: Safety and Risks
Key takeaways:
There isn’t enough human research on Mounjaro® and pregnancy to confirm whether tirzepatide is safe while pregnant.
Animal studies suggest potential risks, like low birth weight and birth defects.
People using Mounjaro® for weight loss are usually advised to stop taking it at least two months before trying to conceive.
If you become pregnant while taking Mounjaro®, stop the medicine immediately and contact your GP. They may suggest another medicine if you have type 2 diabetes.
If you’re pregnant or planning to conceive, you might wonder if you can take Mounjaro® while pregnant.
The short answer is that it’s not recommended. There aren’t enough clinical trials looking at Mounjaro® and pregnancy to verify whether Mounjaro® is safe during pregnancy.
For this reason, medical experts usually recommend avoiding Mounjaro® during pregnancy unless the potential benefits clearly outweigh the risks.
Since the pregnancy risks are unknown, you may be advised to use birth control during the first weeks of taking Mounjaro® and for four weeks after each dose escalation.
Can You Take Mounjaro® While Pregnant?
Most people are advised not to take Mounjaro® while pregnant.
Mounjaro® (tirzepatide) is used to treat obesity and type 2 diabetes. In the United States, it’s also sold under the name Zepbound®, but the U.K. doesn’t have Zepbound® yet.
Mounjaro® is designated as a Black Triangle medicine in the U.K., meaning it’s subject to enhanced safety monitoring. All suspected adverse reactions, including any problems during pregnancy, should be reported via the Yellow Card Scheme.
The Medicines and Healthcare products Regulatory Agency (MHRA) recommends avoiding Mounjaro® while pregnant, breastfeeding, or trying to conceive. The same goes for other weight loss injections, like Wegovy® (semaglutide) and Victoza® (liraglutide).
Mounjaro® and Pregnancy Safety Concerns
The MHRA highlights safety concerns based on animal studies. Tirzepatide (the active ingredient) caused side effects that impacted foetal development, including low birth weight and birth defects (congenital anomalies).
For that reason, it’s best to err on the side of caution and avoid Mounjaro® altogether during pregnancy.
That said, Mounjaro® and other GLP-1 medicines (glucagon-like peptide-1 receptor agonists) are sometimes prescribed for people with type 2 diabetes. Poorly controlled blood sugar during pregnancy can increase the risk of miscarriage, birth defects, and other complications.
In such cases, your GP (general practitioner) or specialist may recommend continuing medication — or using a different form of diabetes medication — to maintain blood sugar control.
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Research on Mounjaro® and Pregnancy
What does the research say about Mounjaro® and pregnancy? Let’s take a look.
Mounjaro® Studies in Humans
Human clinical trials on Mounjaro® and pregnancy are limited. This is partly because it isn’t ethical to intentionally test medications on foetuses.
The only evidence we have is based on pregnancies occurring unawares during GLP-1 peptide-1 receptor agonist trials.
A small study looked at 168 pregnancies of women exposed to GLP-1 receptor agonists during early pregnancy. Taking GLP-1 medication wasn’t associated with a risk of major birth defects compared to having diabetes or overweight or obesity.
A 2023 systematic review looked at human studies of liraglutide and exendin-4, two GLP-1 receptor agonists. In these studies, the medications didn’t cross the placenta. But the studies were extremely small, and they didn’t include Mounjaro® itself.
Animal Studies
Animal studies provide more data:
Pregnant rats given tirzepatide during the organ-formation stage of pregnancy (organogenesis) showed reduced foetal growth, low birth weight, and developmental variations.
Rabbits exposed to tirzepatide had lower foetal body weight. Higher doses were linked to maternal side effects, sometimes causing death of the mother or foetus.
Other research on GLP-1 medicines suggested delayed bone formation (ossification) and altered bone development, often linked to maternal weight loss or reduced food intake.
While results in animals don’t always reflect human outcomes, these findings raise concerns. You can see why most healthcare professionals recommend avoiding Mounjaro® during pregnancy.
Breastfeeding and Mounjaro®
It isn’t clear if tirzepatide passes into breastmilk or whether it affects milk production.
For this reason, most providers recommend avoiding Mounjaro® during breastfeeding. If you wish to breastfeed, your GP can help you weigh the benefits of breastfeeding against the advantages of restarting treatment with GLP-1 medicines.
When to Stop Taking Mounjaro® Before Pregnancy
According to an information sheet on the MHRA website, you should stop taking Mounjaro® (tirzepatide) at least two months before pregnancy.
The MHRA also recommends stopping Wegovy® or Ozempic® (semaglutide) at least two months before pregnancy because it takes longer for semaglutide to exit your system.
If you’re planning a pregnancy, ask your GP for medical advice tailored to your health and goals.
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What to Do if You Get Pregnant on Mounjaro®
If you become pregnant while on Mounjaro®, don’t panic. But still contact your GP or specialist right away.
Your GP may recommend you stop taking Mounjaro® immediately if you were taking it for weight management. Or they might have you switch to a different weight loss medication or diabetes treatment.
Early GLP-1 exposure doesn’t automatically mean problems for your baby. Many women who became pregnant while taking GLP-1 medications have had healthy babies. However, close monitoring throughout pregnancy is important.
What Is an “Ozempic® Baby“?
Many people on GLP-1s claim they fell pregnant unexpectedly. The offspring from these unplanned pregnancies are sometimes called “Ozempic® babies“ — even though it can happen with other weight loss medications.
There are a few possible explanations for this:
GLP-1s might make birth control pills less effective. Consider using a non-oral birth control method (e.g., the vaginal ring), as well as a barrier method of birth control, such as condoms.
Because GLP-1s may benefit metabolism, they might affect fertility. However, this is just a hypothesis that hasn’t yet been tested or proven.
Anecdotally, many report having more sex while on GLP-1s. This could be because of increased sex drive (libido) or confidence. But there’s no data to back this up.
Future research will hopefully reveal more about the link between GLP-1s and fertility.
Mounjaro® and Pregnancy: In Summary
The safety data on Mounjaro® and pregnancy are uncertain. For that reason, it’s recommended that you avoid it during pregnancy.
Remember this:
There’s a lack of human clinical trials on GLP-1s and pregnancy. Animal studies raise concerns about birth defects, low birth weight, and other effects on the unborn baby.
Mounjaro® isn’t recommended during pregnancy. It’s best to avoid weight loss injections if you’re breastfeeding or trying to conceive, too.
You must stop Mounjaro® at least two months before trying to conceive. Use effective contraception during this washout period.
GLP-1s may affect how you absorb oral contraceptive pills, although more data is needed. Discuss contraception with your GP for guidance.
If you’re using GLP-1s for type 2 diabetes, your provider might suggest another treatment. Blood sugar control is critical during pregnancy, but a different treatment option may be safer.
There’s a lot we don’t know about Mounjaro® and pregnancy. For this reason, it’s important to err on the side of caution and avoid taking Mounjaro® while pregnant.
If you’re planning to conceive, discuss your options with your GP in advance. They can advise you on your medication options.
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FAQs
See answers to frequently asked questions about Mounjaro® and pregnancy.
Can you take Mounjaro® when pregnant?
No, Mounjaro® isn’t recommended during pregnancy because it’s unclear whether it’s safe. There’s a lack of data on Mounjaro® and human pregnancies. Research on animal pregnancies and GLP-1s has had concerning conclusions.
What happens if I get pregnant on Mounjaro®?
Stop taking the medication, and speak to your GP immediately if you get pregnant on Mounjaro®. They may recommend you stop taking Mounjaro® and switch to a safer medication option. Your pregnancy exposure should be reported via the Yellow Card Scheme.
Is Mounjaro® safe while breastfeeding?
No. There’s no clear data on whether tirzepatide passes into breastmilk or affects milk production. For this reason, Mounjaro® is not recommended whilst breastfeeding. Most medical professionals advise avoiding it until breastfeeding ends.
Should I stop taking Mounjaro® before trying for a baby?
Yes. The MHRA recommends stopping Mounjaro® at least two months before conception. Ask your GP or specialist about safe alternatives for blood sugar control or weight management.
Do I need contraception while on Mounjaro®?
Yes. Since pregnancy risks are unknown, you may be advised to use contraception, especially in the early weeks of treatment and after dose increases. Mounjaro® may affect how your body absorbs oral birth control. You might want to switch to a non-oral contraceptive, like an IUD (intrauterine device), patch, or vaginal ring. Or use an additional form of contraception, like condoms.
This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your GP about the risks and benefits of any treatment.