Breastfeeding is widely recognized as the optimal source of nutrition for infants, offering a range of benefits that infant formula cannot replicate. However, postpartum mothers often grapple with weight management, leading to interest in weight loss medications like semaglutide and tirzepatide. This article examines the safety of using weight loss injections, specifically semaglutide and tirzepatide, during breastfeeding, considering the potential transfer of these drugs into breast milk and their possible effects on infants.
The Importance of Breastfeeding
Breast milk is considered the best source of nutrients for infants. It contains various bioactive compounds that support gastrointestinal and immune system function, as well as brain development. Breast milk composition changes dynamically to support infant health, something impossible to simulate with infant formula. Furthermore, breastfeeding has been shown to reduce the maternal risk of metabolic disorders later in life, offering protection against obesity and type 2 diabetes. Beyond the nutritional and physical benefits, breastfeeding is cost-effective, convenient, and promotes bonding between mother and child.
Postpartum Weight Changes and the Role of GLP-1 Agonists
Pregnancy often leads to significant weight gain, and many women experience challenges in returning to their pre-pregnancy weight. For instance, one study found that approximately 40% of women with a normal weight before pregnancy and 60% of women classified as overweight experienced excessive weight gain during their pregnancy. Long-term studies have revealed that only 35% of overweight women return to within 1.5 kg of their pre-pregnancy weight, compared to 60% of normal-weight women. Retaining three or more body mass index (BMI) units during a two-year period between births increases the risk of adverse pregnancy outcomes for both mother and infant.
In this context, glucagon-like peptide-1 (GLP-1) agonists like semaglutide have emerged as therapeutic options for weight loss. Semaglutide, besides being a therapeutic option for type 2 diabetes, serves as an anti-obesity drug.
Semaglutide: Mechanism of Action and Use
Semaglutide is an incretin mimetic that binds to GLP-1 receptors. The natural GLP-1 hormone, consisting of about 30 amino acids, inhibits glucagon release from the alpha cells of the pancreas. Semaglutide shares a 94% structural similarity to human GLP-1, differing primarily by an elongated hydrophilic spacer that extends its lifespan via albumin binding. This modification allows for a weekly dosing schedule.
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Semaglutide is available in both injectable and oral forms. Injectable semaglutide (Ozempic, Wegovy) is administered subcutaneously, while oral semaglutide (Rybelsus) is formulated with a permeation enhancer (SNAC) to overcome its low oral bioavailability. Semaglutide's impact on weight loss is mainly achieved by decreasing energy intake, with limited influence on energy expenditure. It reduces hunger, food cravings, and enhances feelings of fullness, ultimately improving eating control.
Semaglutide and Breastfeeding: Assessing the Risks
Given the increasing interest in semaglutide among lactating mothers, it is essential to assess the potential risks associated with its use during breastfeeding. Pharmaceuticals consumed by the mother can transfer into the milk supply and be indirectly transmitted to the infant during feeding. Young infants have different metabolic capacities than adults, and even limited exposure to hazardous substances can result in harm.
Study on Semaglutide Transfer into Breast Milk
A recent study published in the journal Nutrients investigated the presence of semaglutide in breast milk. Researchers at Texas Tech University used data from the Infant Risk Human Milk Biorepository, which collected milk samples and health information from mother-infant dyads. Milk samples from eight women were collected at 0, 12, and 24 hours post-semaglutide administration. Semaglutide quantification was performed using high-resolution liquid chromatography-mass spectrometry.
Key Findings:
- Semaglutide was not detected in any of the collected human milk samples.
- The limit of quantification (LLOQ) for the method was 5.7 ng/mL.
- A worst-case scenario of the relative infant dose (RID) was calculated using the LLOQ as the drug concentration in milk.
- The maximum RID projected was 1.26%, far below the standard 10% safety threshold.
These findings suggest that semaglutide concentrations in human milk are unlikely to pose clinical concerns for breastfed infants. The researchers estimated that, using an infant milk intake of 150 ml/kg/day and the LLOQ of 5.7 ng/ml, the maximum possible dose of semaglutide an infant could be exposed to was 855 ng/kg/day. Given the average maternal weight of 96 kg delivering 0.56 mg subcutaneous semaglutide weekly, the maximum possible RID using the LLOQ was 1.12%. Moreover, the maximum RID was 1.26% when adjusted for changes in milk concentrations after drug administration.
Considerations and Limitations
While the study found undetectable levels of semaglutide in breast milk, it also highlighted the need for close monitoring of both maternal and infant health. The study emphasized the importance of monitoring maternal nutrient intake, particularly given the catabolic state of lactation and the potential for semaglutide to accelerate weight loss beyond typical postpartum changes.
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The study also acknowledged certain limitations. Achieving steady-state conditions with semaglutide can take more than four months after drug initiation. The weekly administration, inconsistent titration schedules, and the risk of breastfeeding cessation during this extended period posed significant challenges in collecting milk samples at steady state. The study prioritized collecting samples immediately before any dose changes, even if this occurred prior to reaching steady-state concentrations, to maximize the informativeness of the analysis.
Additionally, the semaglutide standard added to human milk as a calibrant ex vivo is assumed to behave exactly like semaglutide present in human milk of mothers taking the drug. There may be inaccuracies in calibration and measurement if the calibration standards do not interact with the milk matrix’s fat and protein components in the same way as in vivo occurring semaglutide does. The reliability of quantitative results would be considerably impacted if such differences exist.
Tirzepatide and Breastfeeding: What the Evidence Says
Tirzepatide is another medication used to improve blood sugar control in adults with type 2 diabetes and for weight management. Like semaglutide, it is available as an injection. While weight loss is generally not recommended during pregnancy, tirzepatide may be considered postpartum.
Current Recommendations
Most weight loss injections, including tirzepatide, haven’t been well studied for breastfeeding moms. Current evidence suggests that tirzepatide is a large molecule and unlikely to pass into breast milk. Data suggests that tirzepatide (Mounjaro) is unlikely to pass into breast milk, and a small study found no detectable levels.
Important Considerations:
- Limited Data: There is limited information available about tirzepatide and human milk.
- Molecular Size: Because it is a large molecule, tirzepatide is not expected to get into breastmilk in large amounts.
- Absorption: The medication is likely to break down in the infant’s gastrointestinal tract and not be well-absorbed by the infant.
General Recommendations and Precautions
Given the limited data on the transfer of weight loss injections into breast milk and their potential effects on infants, it is crucial to exercise caution and consult with healthcare professionals.
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Key Recommendations:
- Consult Healthcare Providers: Postpartum mothers should discuss the use of weight loss injections with their healthcare providers to assess the risks and benefits.
- Monitor Maternal and Infant Health: Close monitoring of both maternal and infant health is essential when using weight loss injections during breastfeeding.
- Ensure Adequate Nutrient Intake: Lactating mothers need to ensure they are meeting their increased nutrient demands, especially given the potential for semaglutide and tirzepatide to reduce appetite and food intake.
- Consider Alternatives: Explore alternative weight management strategies that do not involve medication, such as diet and exercise.
tags: #weight #loss #injections #and #breastfeeding #safety