Does Mounjaro affect pregnancy?
If you’re hoping to get pregnant soon, you may be wondering how Mounjaro (tirzepatide) will affect your chances of conceiving. The same applies if you’re already pregnant or breastfeeding—is the medication safe at these times? What about if you’re looking to avoid a pregnancy?
Since many of Mounjaro’s users are women of reproductive age, there are plenty of people out there with similar questions.
Can you take Mounjaro while pregnant?
The short answer is no. Mounjaro hasn’t been tested on pregnant women, so we don’t know whether there are any risks to an unborn baby. In animal studies, it has been linked to a slightly increased risk of birth defects and low birth weight. Although animal studies don't necessarily represent what would happen in people, there is not enough research on humans to suggest Mounjaro is safe to use in pregnancy.
You should stop taking Mounjaro as soon as you see that faint line on the pregnancy test—and talk to your doctor and antenatal clinic about the next steps. Better still, stop beforehand. Weight loss during pregnancy isn’t recommended anyway, so there wouldn’t be much reason to take Mounjaro pregnant even if it were 100% safe.
All this said, if you were taking Mounjaro before realising you were pregnant, don’t panic too much. One 2023 study, which looked at 900 diabetic women who had taken GLP-1 drugs in early pregnancy, found their babies weren’t at any increased risk of birth defects, compared to those who were taking insulin.
How long before pregnancy should you stop Mounjaro?
The NHS recommends stopping Mounjaro at least a month before pregnancy, (and doctors in the US recommend two months). That’s because it takes up to 30 days for the drug to leave your system, meaning it could affect the foetus if you got pregnant in that time.
Does Mounjaro help with pregnancy?
You may have heard that Mounjaro could boost the chances of getting pregnant. There are lots of reports about women who struggled with fertility issues for years, only to find they got pregnant when losing weight on Mounjaro.
To begin with the bad news—we don’t yet know whether Mounjaro has any effect on fertility. But we do know that weight loss (among those who struggle with their weight) can often make it easier to get pregnant. Being a healthy weight is also associated with healthier pregnancies, lowering your risk of complications like gestational diabetes and pre-eclampsia.
What’s more, some researchers think GLP-1 drugs (the class of drugs that includes Mounjaro) might improve fertility among women with polycystic ovary syndrome (PCOS). As well as boosting insulin sensitivity, these drugs might also tackle the hormonal imbalances that interfere with ovulation.
Can you take Mounjaro while breastfeeding?
Again, this hasn’t been directly tested, so the safest answer here is no. We don’t know how much of the drug is likely to get into your breast milk, nor how this would impact the baby. We also don’t know whether it’s likely to have any effect on milk supply.
It’s possible that the consequences would be minimal. The active molecule in Mounjaro is probably too large to enter breast milk in large quantities, and the baby is unlikely to absorb it well. But since we don’t have a full picture of the risks, it’s definitely best to err on the side of caution.
Does Mounjaro affect your menstrual cycle?
There are no studies that directly link the two, so we can’t say for sure. That said, some users have reported changes. If you have PCOS, you may be used to erratic menstrual cycles, or even a period that goes AWOL. Because Mounjaro can help address hormonal imbalances, it could help restore ovulation and return some regularity to your cycle.
On the other hand, extreme and sudden weight loss can be associated with changes to your menstrual cycle. If your once-regular period has become chaotic, it’s best to talk to your GP.
Does Mounjaro affect birth control?
But what if pregnancy isn’t on your to-do list for the near future? Unfortunately, Mounjaro and contraception aren’t always the best of friends. Mounjaro works in part by slowing the emptying of the stomach, which means it can affect the absorption of contraceptives. In short, your pill might not work as well as it usually does, putting you at greater risk of falling pregnant.
If that’s not something you want to worry about, it’s recommended that you use another form of contraceptive (such as condoms) for the first four weeks after starting Mounjaro. Or you could also consider switching to a non-oral contraceptive such as the coil.
Conclusion
If you’ve had a positive experience with Mounjaro so far, it can be disheartening to think about stopping if you get pregnant. Pregnancy and the postpartum period can be a tricky time from a body image perspective, and if you’ve had to pause Mounjaro, that could add another challenge into the mix.
All this said, if Mounjaro is medically recommended for you, there will be ample opportunity to re-start in future. In the meantime, the priority is to keep yourself and your baby as safe as possible.
And if you’re not pregnant yet, but would like to be, Mounjaro may well prove helpful (see if Voy’s weight loss programme might be right for you). While there are a lot of unknowns here, clearer answers are likely to emerge over the years ahead. In the meantime, it’s wise to prioritise your health—whatever that looks like for you—before embarking on your pregnancy journey.
¹Anala, Alekya Devi, et al. “The Potential Utility of Tirzepatide for the Management of Polycystic Ovary Syndrome.” Journal of Clinical Medicine, vol. 12, no. 14, 2023, p. 4575, doi.org/10.3390/jcm12144575.
²Brentwood (TN). “Tirzepatide (Mounjaro®, Zepbound®).” Mother to Baby | Fact Sheets [Internet]. May 2024. Available from: www.ncbi.nlm.nih.gov/books/NBK605070.
³Cesta, Carolyn, et al. “Safety of GLP-1 Receptor Agonists and Other Second-Line Antidiabetics in Early Pregnancy.” JAMA Internal Medicine, vol. 184, no. 2, 2023, p. 144, doi.org/10.1001/jamainternmed.2023.6663.
⁴“Irregular Periods.” NHS. www.nhs.uk/conditions/irregular-periods. Accessed 18 Nov. 2024.
⁵“Obesity and Pregnancy.” NHS. www.nhs.uk/pregnancy/related-conditions/existing-health-conditions/overweight. Accessed 18 Nov. 2024.
⁶Nuako, Emmanuel, et al. “Pharmacologic Treatment of Obesity in Reproductive-Aged Women.” Current Obstetrics and Gynecology Reports, vol. 12, no. 2, 2023, pp. 138–146, doi.org/10.1007/s13669-023-00350-1.
⁷“Pregnancy and Body Image.” The NIH Web Portal for Information about Maternal Morbidity and Mortality. orwh.od.nih.gov/research/maternal-morbidity-and-mortality/information-for-women/pregnancy-and-body-image. Accessed 18 Nov. 2024.
⁸“Weight Management Before, During, and After Pregnancy.” National Institute of Clinical Excellence. www.nice.org.uk/guidance/ph27/chapter/Recommendations.
