Mounjaro and Pregnancy: What the MHRA Says About Conceiving, Pregnancy and Breastfeeding

Why the medicines are not used in pregnancy

There are no controlled studies of tirzepatide or semaglutide in pregnant women, and there will not be, because it would be unethical to run them. Animal studies showed effects on fetal growth at high doses, which may relate to reduced food intake in the mother rather than a direct effect. On top of that, deliberate weight loss and appetite suppression are not appropriate in pregnancy, when the baby’s growth depends on steady nutrition. So the licence position is precautionary: no known human harm, but no basis to say it is safe either.

What prompted the 2025 warning

Through the Yellow Card scheme the MHRA received a number of reports of pregnancy in women using GLP-1 medicines, some of whom had been told they were unlikely to conceive. Two things were happening. First, weight loss restores regular ovulation in many women with obesity or polycystic ovary syndrome, so fertility returns. Second, the medicines slow stomach emptying, which for tirzepatide in particular can reduce how much of the contraceptive pill is absorbed, especially in the weeks after starting and after each dose increase. The June 2025 update told prescribers and patients about both, and the GOV.UK patient information was updated again in February 2026 with the washout periods above. The reports are of pregnancies, not of harm to babies; the point of the warning is prevention.

If you are planning a pregnancy

• Tell your prescriber before you stop. Stopping abruptly usually leads to regained appetite and weight, and they may suggest a plan for that.
• Allow the washout: at least one month after the last Mounjaro dose, at least two months after the last Wegovy or Ozempic dose. Saxenda (liraglutide) clears within days, so it can be stopped just before trying.
• Start folic acid and any pre-pregnancy checks as normal. Weight lost before conception is retained as a benefit; NICE regards a lower pre-pregnancy BMI as reducing risks in pregnancy.
• Use contraception until the washout is complete if you do not want to conceive during it.

If you find out you are pregnant on treatment

Stop the medicine and contact your GP or book with a midwife as you normally would. Do not panic about the exposure. The UK Teratology Information Service, which advises NHS clinicians, states that use of a GLP-1 medicine in early pregnancy is not in itself a reason to consider ending the pregnancy or to add extra scans beyond routine care, because the available human data, though limited, have not shown a pattern of harm. Your midwife may note the exposure so it can be followed up, and reporting it through Yellow Card helps build the evidence for others.

Breastfeeding

It is not known whether tirzepatide or semaglutide pass into breast milk, and the licences advise against use while breastfeeding. Deliberate calorie restriction is also not advised while establishing feeding. Most prescribers will not restart treatment until breastfeeding has finished; if you are considering restarting sooner, that is a decision to make with your GP rather than a pharmacy questionnaire.

Men and fertility

The pregnancy warnings apply to the person carrying the pregnancy. There is no licence restriction on men taking these medicines while their partner is trying to conceive, and the limited evidence suggests weight loss tends to improve rather than harm sperm quality. As with any medicine, mention it at fertility appointments.