The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Can I Take Mounjaro While Pregnant?
No, Mounjaro (tirzepatide) is not recommended during pregnancy and should be stopped if you become pregnant. If you're planning to conceive or are already pregnant, it's essential to discuss this with your GP or healthcare team. There are safe alternatives for managing weight during and after pregnancy, and specialist NHS services can provide personalised support. This guide explains what you need to know about Mounjaro safety in pregnancy and your options for weight management at this important time.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Why Mounjaro Is Not Recommended in Pregnancy
Mounjaro has not been adequately studied in pregnant women, so the MHRA advises against its use during pregnancy as a precautionary measure. Animal studies suggested potential risks to the developing foetus, though human data are limited. If you become pregnant while taking Mounjaro, you should stop immediately and contact your GP — this is not an emergency, but it does require prompt medical review.
Women of childbearing age taking Mounjaro should use reliable contraception:
- If using oral contraceptives (the pill), add a barrier method or switch to non-oral contraception for 4 weeks after starting Mounjaro and 4 weeks after each dose increase — Mounjaro may reduce oral medication absorption
- Non-oral methods (coil, implant, injection) are unaffected and remain reliable
- Discuss contraception options with your GP or sexual health clinic if you're unsure
If you're planning pregnancy, discuss stopping Mounjaro with your prescriber at least 4 weeks beforehand to allow the medication to clear your system.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Weight Management in Pregnancy — Safe Alternatives
During pregnancy, the goal is not weight loss but safe, healthy weight gain. The NHS recommends:
- For women with a healthy BMI before pregnancy: gain 11.5–16 kg during pregnancy
- For women with overweight (BMI 25–29.9): gain 7–11.5 kg
- For women with obesity (BMI 30+): gain 5–9 kg
Your midwife and GP monitor weight gain and can refer you to a dietitian if needed. After pregnancy, NHS specialist weight management services (tier 3) can help, including prescription options like GLP-1 medication — though not while breastfeeding. If you're concerned about weight during pregnancy, discuss support options with your antenatal team rather than managing alone.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
What should I do if I become pregnant while taking Mounjaro?
Stop taking Mounjaro immediately and contact your GP within a few days to discuss next steps. This isn't an emergency, but it does require medical review. Your healthcare team will monitor your pregnancy and discuss safe weight management options during this time.
Can I restart Mounjaro after giving birth?
Yes, Mounjaro can be restarted after pregnancy, typically after you've stopped breastfeeding. Your GP or specialist weight management service will assess whether it's appropriate and safe for you, considering your individual health and feeding plans. Allow time for your body to recover postnatally.
Are there weight loss injections safe in pregnancy?
No prescription weight loss medications (including Mounjaro, Wegovy, or Saxenda) are recommended during pregnancy. Focus during pregnancy is safe, healthy weight gain. After pregnancy and once breastfeeding is complete, your GP can discuss prescription options with you.
How do I access weight management support if I'm planning pregnancy?
Discuss your plans with your GP. If you're currently on Mounjaro and want to try for a baby, your prescriber can advise when to stop. After pregnancy, NHS tier 3 specialist weight management services can provide ongoing support, though waiting lists vary by region.
Is it safe to take Mounjaro if I might become pregnant?
If there's any chance you could become pregnant, discuss reliable contraception with your GP. The UK recommends non-oral contraception (coil, implant) or adding a barrier method to oral contraceptives while on Mounjaro. Plan ahead if you're considering pregnancy in the near future.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.