What Happens If You Fall Pregnant on Mounjaro (October 2026)

01 · Your next steps

What to do if you fall pregnant on Mounjaro

Stop injecting and tell your prescriber promptly. The product information says Mounjaro must not be used during pregnancy, and that if you become pregnant during treatment you should stop the medicine and tell your prescriber.¹¹³

Do not inject another dose while you wait for an appointment. If your next injection day arrives before you have spoken to anyone, skip it.

02 · Do you need this?

Are you pregnant, trying, or just checking?

If you have a positive test, stop Mounjaro and tell your prescriber promptly. If you are late or unsure, take a test and speak to a pharmacist or your prescriber before your next injection.

If you are not pregnant but want to avoid it, the contraception details matter most. If you want to conceive, planning ahead is far better than stopping in a hurry. The weight loss clinic page explains how treatment works alongside your wider health.

Related guides: What happens if you over eat on mounjaro and What happens if you freeze mounjaro.

Related guide: Fell pregnant on mounjaro.

03 · Why it can happen

Why pregnancy can happen on Mounjaro

Yes, you can fall pregnant while taking Mounjaro. It is not a contraceptive, and nothing in its licence says it prevents pregnancy. Several things make an unplanned pregnancy more likely than people expect.

The first is the pill. Mounjaro slows stomach emptying, which can reduce how well oral contraceptive pills are absorbed.¹ If you rely on the pill and do not add cover, protection may be lower than you assume.

The second is fertility itself. Weight loss can improve cycles in women with PCOS or other weight-related fertility problems. That can mean ovulation returns when you did not expect it. The third is simple: people stop being careful because they believe they are less fertile than they are.

04 · Contraception rules

Contraception while taking Mounjaro

The pill is the method affected; most other methods are not. The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹⁷

This applies to the pill only — implants, coils and injections are unaffected.¹ The dose ladder runs from 2.5mg up to a maximum of 15mg, with at least 4 weeks on each dose, depending on how you respond.¹

• Tell your prescriber which contraception you use before you start.
• If you take the pill, add condoms or switch to a non-oral method for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.
• Put the dose-increase dates in your phone so you do not forget the extra cover.
• Ask about long-acting methods if you would rather not think about this at every dose change.

Treatment is supplied only after an online consultation reviewed by a GPhC-registered prescriber, so mention your contraception and any fertility plans there.

05 · Weight loss and fertility

Why you can get pregnant after losing weight

Losing weight can restore ovulation, which is why some people conceive unexpectedly after years of difficulty. Mounjaro is not licensed specifically for PCOS, but many women with PCOS meet the standard weight-management criteria. Weight loss is a first-line recommendation that can improve insulin resistance, cycles and symptoms.

That is good news if you want a baby and a real risk if you do not. If you have irregular periods or a history of difficulty conceiving, do not assume you are protected. Treat every cycle as potentially fertile unless your contraception is reliable.

Tell your prescriber about PCOS and any fertility plans in your consultation. They can then plan treatment with that in mind rather than leaving you to find out the hard way.

06 · Trying to conceive

If you want to get pregnant

Plan the stop date rather than stopping on a whim. The product information says Mounjaro should be stopped at least one month before trying to conceive.¹ Remember too that the medicine takes roughly four to five weeks to clear after a final dose.¹

Speak to your prescriber and your GP before you stop. They can discuss how to maintain your progress with diet and activity, and when to start trying.

Weight can change after treatment stops, and that is worth discussing with your care team in advance rather than being surprised by it.

07 · Tests and symptoms

Pregnancy tests, symptoms and Mounjaro

Standard home pregnancy tests can be read in the usual way. If you are unsure of a result, repeat the test a few days later or ask a pharmacist.

The harder part is spotting early pregnancy. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹ Those are also common early pregnancy signs, so they can mask or mimic one another. A missed period is the clearer clue, though cycle changes can happen with weight loss as well.

If anything new or worrying develops, speak to your prescriber, and report suspected side effects through the Yellow Card scheme.¹⁹

What your maternity team can do is far more useful than a generic statistic: they know your history, your dates and your health. Give them your last injection date and the doses you took, and ask whatever you need to ask.

If you take tirzepatide for type 2 diabetes, your prescriber will also plan how your blood sugar is managed once it stops. Do not stop other diabetes medicines on your own.

08 · Breastfeeding

Breastfeeding and Mounjaro

Current prescribing information indicates minimal transfer of tirzepatide into breast milk; discuss breastfeeding with your prescriber so the decision reflects your circumstances.¹ Tell your midwife or health visitor about any treatment you are considering after birth.