Weight loss drugs and pregnancy – what you need to know

Robert Price | Last update: 6th June 2025

The MHRA has issued an urgent reminder: women taking these treatments must use effective contraception. Here’s why, and what it means for your health and safety.

Why the warning?

There have been increasing reports of unplanned pregnancies among women using GLP-1 treatments (drugs like Wegovy or Mounjaro), even some who were already on contraception. The MHRA has received over 40 pregnancy-related reports so far, prompting this stronger advice.

There are two key concerns behind the warning:

Not enough is known about safety in pregnancy.

There’s limited data on the effects of GLP-1 treatments during pregnancy. Human research is lacking because pregnant women and those planning pregnancy were excluded from trials.

Contraceptive pills may be less effective.

Some treatments, particularly Mounjaro (tirzepatide), slow how quickly your stomach empties. This could affect how oral contraception is absorbed, reducing its effectiveness.

Increased fertility = Higher pregnancy risk

GLP-1 treatments can also increase your fertility. As weight reduces, hormone balance often improves – making it easier to get pregnant, even if you’ve previously struggled.

Reports have shared examples of women who became pregnant on Mounjaro while taking the pill – despite having fertility issues like PCOS. The BBC and Mail Online have highlighted other examples. It’s an important reminder to take contraception seriously while on treatment.

What should you do?

Here’s the key advice from the MHRA and clinical experts:

Use effective contraception
If you’re on a GLP-1 treatment and can become pregnant, use reliable contraception. This can include the pill, implant, coil, or condoms.

Mounjaro users – take extra care
If you’ve been prescribed Mounjaro, consider using a non-oral contraceptive method- especially during the first 4 weeks of treatment and after any dose increase.

If you become pregnant
Stop using your GLP-1 treatment and contact your doctor or healthcare provider immediately. These treatments are not recommended during pregnancy or while trying to conceive.

Planning a pregnancy?
You may need to wait before trying. The time period for weight loss drugs leaving your system is reported as:

• • 2 months after stopping Ozempic or Wegovy
  • 1 month after stopping Mounjaro

This should be planned with a fertility specialist to ensure it’s done safely.

Additional safety reminders

The MHRA also repeated some important guidance for all users:

• Only use legitimate sources
  These are prescription treatments. Never buy them online, or via social media, from unregulated places. Always talk to your doctor or healthcare provider about your treatment.
• Watch out for your side effects
  These treatments can have a range of side effects. Make sure you understand what they are and ask for advice if you’re unsure.
• Report anything unusual
  You can report any side effects or issues through the MHRA’s Yellow Card scheme.

SlimrChat’s final word

These treatments can be effective and life-changing, but they must be used safely. Speak to your doctor or pharmacist if you’re unsure about contraception, pregnancy planning or side effects.

We’ll keep bringing you updates that matter. Stay informed, stay supported, and keep asking questions.