Weight-loss injections and women’s health: cycle, PCOS, trying to conceive and menopause

Body fat is hormonally active. Among other things, it affects oestrogen and testosterone levels, and with severe overweight this can suppress ovulation. When you lose weight quickly on a weight-loss injection, this balance shifts. Some women report more irregular, heavier or lighter bleeding; others find that their cycle suddenly becomes regular again.

On top of that, eating much less puts your body under stress. A very low calorie intake can also throw your cycle off. So make sure you get enough protein and nutrients – more on this in Eating well on a weight-loss injection.

There is hardly any good study data on cycle changes with GLP-1 drugs. So don’t simply blame changes on the injection – have them checked by a gynaecologist, especially if your period stops. In that case, a pregnancy test comes first.

In polycystic ovary syndrome (PCOS), insulin resistance and overweight often play a big role. The German S2k guideline presented in July 2025 relies on lifestyle changes, including weight reduction if you are overweight. Depending on symptoms and whether you want children, medicines such as the pill, metformin or anti-androgens are added.

GLP-1 drugs are not approved for PCOS, so using them would be off-label. A meta-analysis in the European Journal of Endocrinology (Forslund and colleagues, 11 randomised trials) found moderate, short-term weight loss. There were signs of a more regular cycle, but the certainty of evidence was very low. Most studies were small, lasted only 12 to 32 weeks and had methodological weaknesses. Newer drugs such as tirzepatide have barely been studied in PCOS so far.

In other words: the injection may help through weight loss, but it is not a proven PCOS treatment. The decision belongs with a gynaecologist or endocrinologist – not least because of the contraception question.

On social media, women report unplanned pregnancies while on Ozempic, Wegovy or Mounjaro. The media call them “Ozempic babies”. There are no reliable figures yet. According to the Pharmazeutische Zeitung, the German pharmacists’ drug commission (AMK) had not received any such reports.

The effect is still plausible: when weight drops, hormone levels and ovulation often normalise again in people with overweight or PCOS. With tirzepatide there is the added factor that it can reduce absorption of the pill (see below). If you don’t want to get pregnant, check your contraception deliberately – even if it “never worked” for years.

Tirzepatide slows gastric emptying. According to the EU prescribing information, after a single 5 mg dose the peak concentration of a pill oestrogen fell by 59 % and total absorption by 20 %. The EU prescribing information nevertheless does not call for a dose adjustment of the pill and generally recommends that women of childbearing age use contraception.

The UK medicines regulator MHRA is more cautious: it advises using an additional non-oral method such as condoms for four weeks after starting and after each dose increase, or switching to a coil, implant and the like. This does not apply in the same way to semaglutide. You’ll find all the details in the guide Weight-loss injections and the pill.

Neither drug is recommended during pregnancy. The reasons are the long duration of action and the lack of safety data in humans. If you become pregnant while on the injection, talk to your doctor straight away. The drug will then be stopped. Don’t make rash decisions out of fear – your doctor will put the risk into context.

On breastfeeding the picture is mixed: the current EU prescribing information for Mounjaro is fairly relaxed, while the MHRA advises against breastfeeding with all GLP-1 drugs. Decide this with your doctor or midwife. For unapproved substances such as retatrutide or research tirzepatide there are no data at all – they are off-limits during pregnancy and breastfeeding.

If you are trying to conceive, you can proceed like this:

• Talk to your gynaecologist and your prescribing doctor early, ideally months before you plan to start trying
• Agree on when to stop together and keep using reliable contraception until then
• Work out how you will keep your weight stable after stopping – some of it often comes back
• If you have PCOS or diabetes, plan your pregnancy care in advance

How to come off treatment well is covered in Stopping weight-loss injections. This is general information, not medical advice.

During menopause, fat often shifts towards the belly and muscle mass is lost more easily. GLP-1 drugs are not approved specifically for this stage of life, but for overweight or type 2 diabetes – regardless of age. Especially during menopause, plenty of protein and strength training are important to keep your muscle while losing weight (see Avoiding muscle loss).

Irregular bleeding can have many causes at this stage and should always be checked by a gynaecologist. What Mounjaro can feel like during menopause is described in Alexandra’s personal experience report. That is one person’s experience, not evidence.