Woman says off-label Mounjaro treatment preceded unexpected pregnancy and birth

A woman who said she had long struggled with obesity and irregular menstrual cycles says she conceived naturally at 41 and later gave birth to a son after 18 months of self-administered Mounjaro (tirzepatide) injections she had been using to lose weight.

The woman, now 42, told a British newspaper she had been told by clinicians that conception would be unlikely without assisted reproduction because of her health and weight. She said she began taking Mounjaro in the hope of losing enough weight to attempt in vitro fertilization, and that the positive pregnancy test came as a shock. She described watching her 10-month-old son grow and said she believes the drug helped restore her health and fertility.

In accounts published by the woman, she said she had struggled with obesity since childhood and experienced menstrual cycles that could last up to 90 days, along with excess facial hair — symptoms commonly associated with polycystic ovary syndrome (PCOS). She said she weighed about 23 stone (roughly 322 pounds) at age 39 and had been preparing for fertility treatment, including plans for IVF, when she began using tirzepatide.

Tirzepatide, marketed in some countries as Mounjaro for the treatment of type 2 diabetes, has been used off-label by some people for weight loss. The woman said she administered injections herself for about a year and a half before discovering she was pregnant; she said the injections were not fertility drugs. She declined, in the published account, to provide medical records and described her pregnancy and the birth of her son as a "miracle."

Medical experts and professional guidance emphasize that weight loss can restore ovulation and improve fertility for some people with obesity and PCOS, but the effects of specific medications on conception and pregnancy outcomes vary and are not fully established. Clinicians caution that many of the newer diabetes and weight-loss medications have limited data on safety in pregnancy, and medical advice typically recommends consulting a clinician when planning pregnancy or when pregnancy occurs.

The woman's account adds to anecdotal reports from patients who have used GLP-1 receptor agonists and related drugs for weight loss and later experienced changes in menstrual patterns or fertility. Researchers continue to study the broader physiologic effects of these therapies, including potential impacts on reproductive hormones, ovulation and pregnancy outcomes. Regulatory approvals and clinical guidance differ by jurisdiction, and not all drugs used for weight management were originally developed or approved for that indication.

Public-health officials and many clinicians advise that pregnant people or those trying to conceive should seek medical counsel before starting or continuing medications initially prescribed for diabetes or weight management. Some drugs are contraindicated in pregnancy, and treatment plans are often individualized to balance potential benefits and risks for both parent and fetus.

The woman said she had initially planned to pursue IVF once she had lost weight, but the spontaneous pregnancy altered that trajectory. She described the emotional impact of becoming a mother after years of believing pregnancy would be unlikely, and said she attributes improved health and the birth of her son to the weight loss she achieved while on tirzepatide.

Researchers and clinicians who study fertility and metabolic treatments say larger, controlled studies are needed to clarify how specific weight-loss medications affect fertility and pregnancy. Until more definitive evidence is available, guidance typically centers on preconception counseling, individualized risk assessment and coordination between primary care, endocrinology and obstetrics providers when pregnancy is planned or occurs while taking metabolic medications.