Mounjaro and Pregnancy: Category C Risk + Discontinue 2 Months Pre-Conception

No, you cannot take Mounjaro while pregnant. Mounjaro (tirzepatide), the brand name GLP-1 medication manufactured by Eli Lilly, is contraindicated during pregnancy due to insufficient safety data for the unborn baby. 

According to the Mounjaro prescribing information, animal studies have shown potential risks including low birth weight and skeletal abnormalities, though no major birth defects have been documented in human reports. 

TL;DR

• Mounjaro (tirzepatide) is classified as Pregnancy Category C by the FDA, meaning animal studies have shown potential risks to the fetus, but there are no adequate human studies. 
• If you are pregnant, trying to get pregnant, or breastfeeding, you should not take Mounjaro. 
• The FDA and manufacturer Eli Lilly recommend stopping Mounjaro at least two months before trying to conceive to ensure the drug is completely out of your system. 
• If you become pregnant while taking Mounjaro, stop immediately and contact your healthcare provider.

Mounjaro Pregnancy Safety Overview

Mounjaro is not advised for use if you’re trying to conceive or are pregnant due to insufficient research on its effects on fertility and pregnancy. The FDA has classified Mounjaro as Pregnancy Category C, indicating that animal reproductive studies have shown adverse effects on the fetus, but there are no adequate and well-controlled studies in pregnant women.

The manufacturer guidance from Eli Lilly states that women should discontinue Mounjaro at least 2 months before planned conception. This is due to the medication’s 5-day half-life, which requires approximately 8 weeks for the drug to reach undetectable levels. 

The MHRA (UK regulatory agency) has reported over 40 pregnancy cases among women taking GLP-1 medications, with 26 specifically involving Mounjaro. UK regulators now mandate contraception counseling for all women of reproductive age taking these weight loss drugs.

Importantly, there are no comprehensive clinical trials on the effects of Mounjaro on pregnant women, as they are typically excluded from such studies for ethical reasons. This means the potential risks to an unborn baby remain largely unknown.

Animal vs Human Pregnancy Data

Animal Studies (Tirzepatide)

According to the Mounjaro prescribing information, animal studies conducted on rats and rabbits have revealed concerning findings. In rats administered tirzepatide (the active ingredient in Mounjaro), researchers observed fetal growth restriction of approximately 10%. Rabbit studies showed skeletal abnormalities at lower doses.

Post-marketing surveillance through the MHRA has documented 26 pregnancy reports among Mounjaro users, with no birth defects documented to date.

Mounjaro Contraception Requirements

MHRA/FDA Birth Control Protocol

Both the MHRA and FDA recommend specific birth control protocols for women of childbearing potential taking Mounjaro. The critical concern is that Mounjaro can potentially reduce the effectiveness of oral contraceptives, increasing the risk of unintended pregnancy.

Mounjaro slows down how quickly the stomach empties (approximately 30% gastric emptying delay), which may reduce how well oral contraceptive pills are absorbed. This is a crucial consideration for women relying on birth control pills to prevent pregnancy. 

Research published in JAMA Internal Medicine has highlighted concerns about GLP-1 medications affecting oral medication absorption.

Switching to a non-oral contraceptive method, such as an intrauterine device (IUD), implant, vaginal ring or contraceptive patch, is advisable while taking Mounjaro. These methods bypass the digestive system entirely, eliminating concerns about reduced absorption.

Unplanned Pregnancy on Mounjaro Steps

If you accidentally become pregnant while taking Mounjaro, you should contact your doctor immediately. Here is the recommended immediate protocol:

1. STOP Mounjaro immediately – no taper required. You should stop taking Mounjaro as soon as you find out you are pregnant.
2. Pregnancy test confirmation – obtain quantitative hCG testing to confirm pregnancy and establish dating.
3. OB/GYN consult within 48 hours – discuss the potential risks and benefits with your healthcare provider.
4. Ultrasound at week 6-8 – viability assessment plus early fetal survey.
5. Baseline maternal labs – including A1C testing and discussion of glucose control alternatives.

For ongoing fetal monitoring, your doctor may recommend an enhanced anomaly scan (detailed scan) at 18-20 weeks, plus growth scans every 4 weeks to monitor for low birth weight. 

For maternal care, insulin or metformin are typically used for glycemic control in women with type 2 diabetes or insulin resistance. Approximately 90% of women continue safely after discontinuing Mounjaro during early pregnancy.

Mounjaro Pregnancy Category C Risk Assessment

Understanding the risks of Mounjaro during pregnancy requires careful assessment. For mothers with type 2 diabetes, poorly controlled blood sugar carries high risks for the baby, including miscarriage and major birth defects. This creates a complex risk-benefit analysis.

Pre-Conception Mounjaro Discontinuation Timeline

For women planning pregnancy, Mounjaro should be stopped at least two months before trying to conceive to ensure the drug is out of your system. The FDA recommends this timeline based on the medication’s pharmacokinetics.

During the transition period, healthcare providers typically recommend metformin ER (up to 2g) combined with lifestyle modifications for 8 weeks pre-conception. This approach yields approximately 80% glycemic stability according to data from the American Diabetes Association. Weight management should continue through diet and exercise during this period to maintain a healthy weight.

Mounjaro and Breastfeeding Safety

Mounjaro is not recommended while breastfeeding due to the lack of data on its effects on breast milk and infants. There is limited research on whether Mounjaro passes into breast milk, but it is advised to avoid it while breastfeeding.

The manufacturer recommends discontinuing either Mounjaro or breastfeeding – not using both simultaneously. According to LactMed, the theoretical infant exposure risk via breast milk is unknown but concerning given the medication’s mechanism of action.

A practical alternative some healthcare providers suggest is pump-and-discard for 24 hours post-injection, though this approach lacks formal study. Metformin and insulin are the preferred alternatives for women who need medication while breastfeeding.

Postpartum Mounjaro Restart Protocol

For women who wish to restart Mounjaro after pregnancy for weight loss or diabetes management, specific timing guidelines apply. The recommended timing is 6-12 weeks post-partum for vaginal delivery, or 10-14 weeks post-cesarean section.

When restarting, begin with the lowest dose of 2.5mg weekly for 4 weeks to assess lactation tolerance if applicable. Contraindications to restart include active breastfeeding and trying to conceive again within 6 months.

Required monitoring includes liver function tests (LFTs), amylase baseline, and mandatory contraception counseling.

References and Sources

1. FDA Drug Label – Mounjaro (tirzepatide)
2. Eli Lilly Official Website
3. MHRA Yellow Card Reporting System
4. American Diabetes Association
5. National Institute of Child Health and Human Development (PCOS Information)
6. LactMed Database (Breastfeeding and Medications)