Mounjaro and Fertility in Women: What the Evidence Says

Should you stop Mounjaro if you are trying for a baby?

Yes, and this is probably the question our prescribers hear most weeks from women in their thirties who started treatment for weight management and are now thinking about family planning. The short answer is clear: Mounjaro is not recommended during pregnancy or when actively trying to conceive, and the guidance from NHS England is that women should use effective contraception throughout their treatment course.

The reasoning matters. Animal studies at high tirzepatide doses showed adverse effects on foetal development. There is no adequate human safety data for early pregnancy, so the precautionary position is firm. Once you have decided to try for a pregnancy, stopping Mounjaro and allowing a wash-out period before conception is the correct path. The appropriate length of that gap is a conversation to have with your GP or specialist, because it depends on how long you have been on treatment, your current dose, and your individual circumstances. Our detailed page on how Mounjaro may affect female fertility covers the hormonal mechanisms in more depth.

One practical point that catches people out: women using the oral contraceptive pill alongside tirzepatide should add a barrier method for the first four weeks of starting treatment and for four weeks after any dose increase. Tirzepatide slows gastric emptying, which can reduce the absorption of oral medications taken at the same time, including the pill. Start your free consultation to discuss contraception alongside your treatment plan.

Can Mounjaro actually improve fertility for some women?

This is where the evidence becomes more nuanced, and honesty requires holding two things at once: Mounjaro is not a fertility treatment, and yet weight loss (achieved through any means) is well established to improve reproductive hormone balance in women with obesity-related disruption.

Excess body weight can raise oestrogen levels, disrupt the hypothalamic-pituitary-ovarian axis, and suppress ovulation. Conditions such as polycystic ovary syndrome (PCOS) are strongly linked to insulin resistance and adiposity, and both of those are targets tirzepatide was designed to address. Women who lose significant weight often see improvements in cycle regularity, ovulation frequency, and androgen levels. Given the scale of weight reduction seen in clinical trials (the SURMOUNT-1 trial published in the New England Journal of Medicine reported an average body-weight reduction of around 20–21% at the highest dose) it is plausible that some women experience improved reproductive function as a downstream benefit.

Plausible is not the same as proven, however. Tirzepatide has not been studied as a fertility intervention. Whether any individual woman's fertility improves, and by how much, depends on the underlying cause of any difficulty, factors a reproductive specialist is best placed to assess. Our broader Mounjaro and fertility page explores what the current evidence base does and does not yet confirm.

What should you tell your doctor before starting Mounjaro?

Any woman of reproductive age should be transparent with their prescriber about their family-planning intentions before starting tirzepatide. This is not a box-ticking exercise. It shapes decisions about contraception, timing, and how long a course of treatment makes sense given your goals.

If you have a diagnosis that already affects fertility (PCOS, hypothalamic amenorrhoea, premature ovarian insufficiency) your prescriber needs to know, both because it may be relevant to whether Mounjaro is suitable and because weight changes can alter the picture in ways your wider care team should monitor. The NHS England guidance on weight-management injections sets out the contraception and HRT considerations for tirzepatide clearly and is worth reading before your consultation.

If you are already under the care of a fertility clinic or reproductive endocrinologist, let them know you are considering or taking tirzepatide. These conversations should happen in parallel, not sequentially. At nume, every consultation is reviewed personally by a GPhC-registered Independent Prescriber, and questions about reproductive health are taken as seriously as any other clinical factor. Understanding how tirzepatide interacts with reproductive hormones is a useful next step before that conversation.

What happens after you stop Mounjaro, does fertility return to normal?

Tirzepatide itself does not permanently alter reproductive biology. Once you stop treatment and the medicine clears your system, there is no known mechanism by which it causes lasting hormonal disruption. For most women, any effects on ovulation or cycle regularity that emerged during treatment would relate to changes in body weight or insulin sensitivity rather than to the drug itself.

That said, returning fertility is not guaranteed by stopping a medicine. If the underlying driver of any reproductive difficulty was weight-related hormonal imbalance, and if treatment has resulted in meaningful weight loss, some women find their reproductive health is in a better position than before they started, though this varies considerably. Others will need specialist support regardless. The MHRA's Yellow Card scheme is the right place to report any unexpected reproductive or gynaecological changes experienced during or after GLP-1 treatment.

For women thinking about timing (finishing a course of Mounjaro, allowing a wash-out period, then trying to conceive) the sequencing is best planned with your GP or a reproductive specialist who knows your full history. Couples planning together may also want to read our page on how Mounjaro can affect male fertility, and our dedicated guide to Mounjaro and fertility in men goes into further detail on what the evidence currently shows for male reproductive health specifically.