Mounjaro and Fertility: What Women Need to Know Before and During Treatment

Mounjaro and fertility is a topic that many women of reproductive age ask about before starting tirzepatide treatment. If you are planning a pregnancy, undergoing fertility treatment, or simply want to understand how Mounjaro might affect your reproductive health, this guide covers what the clinical evidence shows and what your doctor needs to know.

At CutKilo, our doctors discuss fertility and contraception with every woman of childbearing age before prescribing Mounjaro. Here is the clinical picture, drawn from the MHRA SmPC, NICE guidance, and the published trial data.

No. The MHRA SmPC for tirzepatide (Mounjaro) states clearly that the medication should not be used during pregnancy or in women who are actively trying to conceive. Animal studies have shown adverse effects on foetal development at high doses, and there are insufficient human data to confirm safety in pregnancy. If you are planning a pregnancy, you should stop Mounjaro at least one month before attempting to conceive, owing to the long half-life of the drug (approximately five days).

However, this does not mean Mounjaro is harmful to your long-term fertility. In fact, for many women with obesity-related subfertility, losing weight before conception can significantly improve reproductive outcomes.

Obesity is one of the most common modifiable risk factors for female subfertility. Excess adipose tissue disrupts the hormonal signals that regulate ovulation, particularly by increasing oestrogen levels through peripheral aromatisation and by promoting insulin resistance. This hormonal imbalance can lead to irregular or absent menstrual cycles, anovulation (failure to release an egg), and reduced conception rates.

Research published in The Lancet Diabetes & Endocrinology has shown that women with a BMI above 30 are significantly less likely to conceive naturally and have lower success rates with assisted reproduction techniques such as IVF. NICE Clinical Guideline CG156 on fertility recommends that women with a BMI of 30 or above should be advised to lose weight before starting fertility treatment.

This is precisely where Mounjaro can play a valuable role. By helping women achieve clinically meaningful weight loss before conception, tirzepatide may indirectly improve fertility outcomes, even though it must be stopped before pregnancy begins.

Yes, and the mechanism is well established. The SURMOUNT-1 trial, published in The New England Journal of Medicine, demonstrated that tirzepatide produced average weight losses of 15 to 22.5 per cent of body weight over 72 weeks, depending on the dose. For a woman weighing 100 kg, that represents a loss of 15 to 22.5 kg, which is enough to substantially improve hormonal balance, restore regular ovulation, and increase the likelihood of natural conception.

Weight loss also improves insulin sensitivity, which is particularly relevant for women with polycystic ovary syndrome (PCOS). If you have PCOS and are struggling with your weight, you may find our guide on Mounjaro and PCOS helpful for understanding how tirzepatide can support menstrual regularity.

PCOS is the most common cause of anovulatory infertility in the UK, affecting approximately 1 in 10 women of reproductive age. Insulin resistance is a core feature of the condition, and GLP-1 receptor agonists like tirzepatide directly target this metabolic pathway.

By reducing insulin resistance and promoting weight loss, Mounjaro can help restore the hormonal environment needed for regular ovulation. Published data on GLP-1 receptor agonists in women with PCOS have shown improvements in menstrual cycle regularity, reductions in circulating androgen levels, and improved markers of metabolic health. While tirzepatide is not licensed specifically for PCOS or fertility treatment, these metabolic benefits are well documented.

It is worth noting that as menstrual cycles become more regular with weight loss, the chance of an unplanned pregnancy increases. This is why contraception counselling is such an important part of prescribing Mounjaro to women of childbearing age.

The MHRA SmPC for tirzepatide includes a specific warning about oral contraceptive pills. Because Mounjaro slows gastric emptying (the rate at which the stomach passes food and medication into the small intestine), it may reduce the absorption of oral medications taken at the same time, including the combined oral contraceptive pill and the progestogen-only pill.

Clinical pharmacokinetic studies have shown that tirzepatide reduced the peak concentration (Cmax) and overall exposure (AUC) of co-administered oral contraceptives. While the clinical significance of this reduction is still being studied, the SmPC advises that women using oral hormonal contraceptives should either switch to a non-oral method or use additional barrier contraception (such as condoms) while taking Mounjaro.

Non-oral contraceptive options that are unaffected by gastric emptying include the hormonal coil (IUS, such as Mirena), the copper coil (IUD), the contraceptive implant (Nexplanon), and the contraceptive injection (Depo-Provera). The Faculty of Sexual and Reproductive Healthcare (FSRH) provides guidance on all of these methods, and your GP or CutKilo doctor can help you choose the most suitable option.

If you are planning a pregnancy, you should discuss your timeline with your prescribing doctor well in advance. The MHRA SmPC recommends discontinuing tirzepatide at least one month (four weeks) before attempting to conceive. This washout period allows the drug to be fully cleared from your system, given its elimination half-life of approximately five days.

During this transition period, your doctor can help you develop a plan to maintain your weight loss through dietary and lifestyle strategies. The goal is to reach a healthier weight on Mounjaro, stop the medication, and then conceive at a BMI that gives you and your baby the best possible outcomes.

If you discover you are pregnant while still taking Mounjaro, stop the medication immediately and contact your doctor. There is no evidence of harm from brief early exposure in humans, but continued use during pregnancy is not recommended based on the available safety data.

While the majority of fertility discussions around Mounjaro focus on women, male fertility can also be affected by obesity. Excess body fat in men is associated with reduced testosterone levels, impaired sperm quality, and lower conception rates. Weight loss through tirzepatide treatment may improve these parameters, though specific studies on tirzepatide and male fertility have not yet been published.

Men taking Mounjaro who are trying to conceive with a partner do not need to stop the medication. There is no evidence that tirzepatide affects sperm in a way that could harm a developing pregnancy.

Will Mounjaro damage my eggs or reduce my egg reserve? There is no evidence that tirzepatide damages oocytes (eggs) or reduces ovarian reserve. The animal studies that raised safety concerns related to foetal development during active pregnancy, not to the long-term health of eggs before conception.

Can I take Mounjaro while undergoing IVF? This should be discussed with both your fertility specialist and your prescribing doctor. Most fertility clinics will advise stopping GLP-1 receptor agonists before starting an IVF cycle, as the effects of delayed gastric emptying on IVF medication absorption have not been fully studied.

Can I breastfeed while taking Mounjaro? The MHRA SmPC states that tirzepatide should not be used during breastfeeding. It is not known whether the drug passes into breast milk, and a risk to the nursing infant cannot be excluded. If you are breastfeeding, discuss alternative weight management options with your doctor.

How long after stopping Mounjaro can I try to get pregnant? The recommended washout period is at least one month (four weeks) after your last injection. Given the five-day half-life, the drug should be effectively cleared from your system within three to four weeks.

Will I regain weight after stopping Mounjaro to conceive? Some weight regain is possible after stopping any GLP-1 receptor agonist. Your CutKilo doctor will help you build sustainable eating and activity habits during treatment so that you are well prepared to maintain your progress. A structured transition plan is part of every CutKilo treatment pathway.

Mounjaro must be stopped before conception and is not suitable during pregnancy or breastfeeding. However, for women with obesity-related subfertility, achieving a healthier weight on tirzepatide before trying to conceive can meaningfully improve your chances of becoming pregnant naturally or through assisted reproduction. Contraception is essential while on treatment, and women using oral hormonal methods should discuss switching to a non-oral alternative with their doctor.

At CutKilo, fertility planning is part of the conversation from day one for women of childbearing age. Your doctor will work with you to create a treatment timeline that supports both your weight-loss goals and your family-planning aspirations.

Mounjaro and fertility is a topic that many women of reproductive age ask about before starting tirzepatide treatment. If you are planning a pregnancy, undergoing fertility treatment, or simply want to understand how Mounjaro might affect your reproductive health, this guide covers what the clinical evidence shows and what your doctor needs to know.

At CutKilo, our doctors discuss fertility and contraception with every woman of childbearing age before prescribing Mounjaro. Here is the clinical picture, drawn from the MHRA SmPC, NICE guidance, and the published trial data.

No. The MHRA SmPC for tirzepatide (Mounjaro) states clearly that the medication should not be used during pregnancy or in women who are actively trying to conceive. Animal studies have shown adverse effects on foetal development at high doses, and there are insufficient human data to confirm safety in pregnancy. If you are planning a pregnancy, you should stop Mounjaro at least one month before attempting to conceive, owing to the long half-life of the drug (approximately five days).

However, this does not mean Mounjaro is harmful to your long-term fertility. In fact, for many women with obesity-related subfertility, losing weight before conception can significantly improve reproductive outcomes.

Obesity is one of the most common modifiable risk factors for female subfertility. Excess adipose tissue disrupts the hormonal signals that regulate ovulation, particularly by increasing oestrogen levels through peripheral aromatisation and by promoting insulin resistance. This hormonal imbalance can lead to irregular or absent menstrual cycles, anovulation (failure to release an egg), and reduced conception rates.

Research published in The Lancet Diabetes & Endocrinology has shown that women with a BMI above 30 are significantly less likely to conceive naturally and have lower success rates with assisted reproduction techniques such as IVF. NICE Clinical Guideline CG156 on fertility recommends that women with a BMI of 30 or above should be advised to lose weight before starting fertility treatment.

This is precisely where Mounjaro can play a valuable role. By helping women achieve clinically meaningful weight loss before conception, tirzepatide may indirectly improve fertility outcomes, even though it must be stopped before pregnancy begins.

Yes, and the mechanism is well established. The SURMOUNT-1 trial, published in The New England Journal of Medicine, demonstrated that tirzepatide produced average weight losses of 15 to 22.5 per cent of body weight over 72 weeks, depending on the dose. For a woman weighing 100 kg, that represents a loss of 15 to 22.5 kg, which is enough to substantially improve hormonal balance, restore regular ovulation, and increase the likelihood of natural conception.

Weight loss also improves insulin sensitivity, which is particularly relevant for women with polycystic ovary syndrome (PCOS). If you have PCOS and are struggling with your weight, you may find our guide on Mounjaro and PCOS helpful for understanding how tirzepatide can support menstrual regularity.

PCOS is the most common cause of anovulatory infertility in the UK, affecting approximately 1 in 10 women of reproductive age. Insulin resistance is a core feature of the condition, and GLP-1 receptor agonists like tirzepatide directly target this metabolic pathway.

By reducing insulin resistance and promoting weight loss, Mounjaro can help restore the hormonal environment needed for regular ovulation. Published data on GLP-1 receptor agonists in women with PCOS have shown improvements in menstrual cycle regularity, reductions in circulating androgen levels, and improved markers of metabolic health. While tirzepatide is not licensed specifically for PCOS or fertility treatment, these metabolic benefits are well documented.

It is worth noting that as menstrual cycles become more regular with weight loss, the chance of an unplanned pregnancy increases. This is why contraception counselling is such an important part of prescribing Mounjaro to women of childbearing age.

The MHRA SmPC for tirzepatide includes a specific warning about oral contraceptive pills. Because Mounjaro slows gastric emptying (the rate at which the stomach passes food and medication into the small intestine), it may reduce the absorption of oral medications taken at the same time, including the combined oral contraceptive pill and the progestogen-only pill.

Clinical pharmacokinetic studies have shown that tirzepatide reduced the peak concentration (Cmax) and overall exposure (AUC) of co-administered oral contraceptives. While the clinical significance of this reduction is still being studied, the SmPC advises that women using oral hormonal contraceptives should either switch to a non-oral method or use additional barrier contraception (such as condoms) while taking Mounjaro.

Non-oral contraceptive options that are unaffected by gastric emptying include the hormonal coil (IUS, such as Mirena), the copper coil (IUD), the contraceptive implant (Nexplanon), and the contraceptive injection (Depo-Provera). The Faculty of Sexual and Reproductive Healthcare (FSRH) provides guidance on all of these methods, and your GP or CutKilo doctor can help you choose the most suitable option.

If you are planning a pregnancy, you should discuss your timeline with your prescribing doctor well in advance. The MHRA SmPC recommends discontinuing tirzepatide at least one month (four weeks) before attempting to conceive. This washout period allows the drug to be fully cleared from your system, given its elimination half-life of approximately five days.

During this transition period, your doctor can help you develop a plan to maintain your weight loss through dietary and lifestyle strategies. The goal is to reach a healthier weight on Mounjaro, stop the medication, and then conceive at a BMI that gives you and your baby the best possible outcomes.

If you discover you are pregnant while still taking Mounjaro, stop the medication immediately and contact your doctor. There is no evidence of harm from brief early exposure in humans, but continued use during pregnancy is not recommended based on the available safety data.

While the majority of fertility discussions around Mounjaro focus on women, male fertility can also be affected by obesity. Excess body fat in men is associated with reduced testosterone levels, impaired sperm quality, and lower conception rates. Weight loss through tirzepatide treatment may improve these parameters, though specific studies on tirzepatide and male fertility have not yet been published.

Men taking Mounjaro who are trying to conceive with a partner do not need to stop the medication. There is no evidence that tirzepatide affects sperm in a way that could harm a developing pregnancy.

Will Mounjaro damage my eggs or reduce my egg reserve? There is no evidence that tirzepatide damages oocytes (eggs) or reduces ovarian reserve. The animal studies that raised safety concerns related to foetal development during active pregnancy, not to the long-term health of eggs before conception.

Can I take Mounjaro while undergoing IVF? This should be discussed with both your fertility specialist and your prescribing doctor. Most fertility clinics will advise stopping GLP-1 receptor agonists before starting an IVF cycle, as the effects of delayed gastric emptying on IVF medication absorption have not been fully studied.

Can I breastfeed while taking Mounjaro? The MHRA SmPC states that tirzepatide should not be used during breastfeeding. It is not known whether the drug passes into breast milk, and a risk to the nursing infant cannot be excluded. If you are breastfeeding, discuss alternative weight management options with your doctor.

How long after stopping Mounjaro can I try to get pregnant? The recommended washout period is at least one month (four weeks) after your last injection. Given the five-day half-life, the drug should be effectively cleared from your system within three to four weeks.

Will I regain weight after stopping Mounjaro to conceive? Some weight regain is possible after stopping any GLP-1 receptor agonist. Your CutKilo doctor will help you build sustainable eating and activity habits during treatment so that you are well prepared to maintain your progress. A structured transition plan is part of every CutKilo treatment pathway.

Mounjaro must be stopped before conception and is not suitable during pregnancy or breastfeeding. However, for women with obesity-related subfertility, achieving a healthier weight on tirzepatide before trying to conceive can meaningfully improve your chances of becoming pregnant naturally or through assisted reproduction. Contraception is essential while on treatment, and women using oral hormonal methods should discuss switching to a non-oral alternative with their doctor.

At CutKilo, fertility planning is part of the conversation from day one for women of childbearing age. Your doctor will work with you to create a treatment timeline that supports both your weight-loss goals and your family-planning aspirations.