Metformin is a medication frequently prescribed for conditions like type 2 diabetes and polycystic ovary syndrome (PCOS). Breastfeeding mothers often wonder how metformin might affect their milk supply and infant safety. This article provides current information on metformin use during lactation, addressing these common concerns.
Metformin’s Influence on Milk Supply
Research indicates that metformin generally does not negatively impact a mother’s breast milk production. For mothers with underlying insulin resistance, such as those with PCOS, metformin may even be associated with improved lactation.
Insulin plays a role in milk production, and disruptions in insulin and glucose metabolism can sometimes lead to a reduced milk supply. Metformin works by improving the body’s insulin sensitivity and glucose control, which could theoretically enhance milk synthesis. While some studies explore this potential benefit, others note that metformin use during pregnancy does not significantly alter overall breastfeeding rates or measured milk volume postpartum.
Metformin Transfer to Breast Milk
Studies consistently show that only small amounts of metformin pass into breast milk. The concentration is typically very low, often ranging from 0.11% to 1% of the mother’s weight-adjusted dosage.
The mean milk-to-plasma ratio, comparing drug levels in milk to the mother’s blood, is also low, around 0.35. This means an infant’s estimated dose is approximately 0.28% of the maternal dose, well below the 10% threshold considered concerning. Metformin levels remain relatively constant, so there is no need to adjust feeding times around medication doses.
Assessing Infant Safety
Due to minimal transfer into breast milk, metformin is widely considered safe for breastfed infants. Studies report no adverse effects on the growth, development, or overall health of babies whose mothers were taking metformin, with the drug often undetectable in infant plasma. However, observe the infant for any unusual symptoms like increased drowsiness, paleness, sweating, or shakiness, especially if premature or with kidney issues.
Guidance from Healthcare Providers
Consulting with a healthcare provider, such as a doctor or lactation consultant, is important before making any decisions about metformin use during breastfeeding. They can discuss your specific medical history, current dosage, and any individual concerns.
Healthcare providers are equipped to weigh the benefits of metformin for the mother’s health against any theoretical risks to the infant, considering factors like the baby’s age and overall health. Generally, mothers can continue their prescribed metformin regimen without needing specific dosage adjustments for lactation.