Metformin is a medication used for the treatment of type 2 diabetes, when diet and exercise have not been effective in controlling blood glucose levels.
Metformin is also used to lower insulin levels in women with polycystic ovary syndrome or to improve insulin sensitivity in women with gestational diabetes.
If you’re a breastfeeding mother, you might wonder: Is taking metformin while breastfeeding safe for my baby?
This article answers common questions asked by nursing mothers about metformin treatment while breastfeeding.
For more information about breastfeeding and diabetes, you can read BellyBelly’s article: Can Diabetes Impact Breastfeeding Success?
Can you take metformin while breastfeeding?
Metformin is considered a safe medication for lactating mothers to take.
The American Diabetes Association, the Global Diabetes Community UK and NPS Medicine Wise Australia all concur that it is unlikely there would be any adverse effects on breastfed infants of mothers on metformin treatment.
It’s always important to check with your healthcare provider before taking any medications while breastfeeding.
Does metformin pass into breast milk?
Metformin passes into breast milk but data from studies suggest that metformin levels detected in the breast milk of lactating women are low.
In women taking 1500 mg of metformin per day, the average estimated amount of metformin passed to their breastfed infants was 0.04 mg/kg of the weight-adjusted maternal dosage.
The milk metformin levels were relatively stable over a 24 hour period, so timing the maternal dose around breastfeeding schedules did not make a significant difference in the metformin levels detectable in breast milk.
Can metformin harm breastfed infants?
The amount of metformin that passes from breastfeeding mothers to their babies is not harmful.
Studies on the transfer of metformin into human milk found no adverse effects on breastfed infants.
In babies of ages ranging from 10 days to 25 months whose mothers were taking metformin while breastfeeding it was reported that:
- The mothers reported no adverse effects in their babies
- There were no detectable adverse effects in the babies
- None of the infants had low blood glucose levels
- The babies met their expected growth and developmental milestones.
Does metformin affect breast milk production?
Metformin is sometimes used to increase breast milk production in breastfeeding mothers with low milk supply. There is currently no scientific evidence of the effectiveness of metformin as a galactagogue (a substance that boosts breast milk production).
In a pilot study on women with low milk supply and symptoms of insulin resistance, researchers tested metformin versus placebo for their effects in treating low milk supply.
The women taking metformin (as opposed to the placebo group) showed no statistically significant difference in baseline measurements of breast milk output after two to four weeks of metformin treatment.
For natural alternatives used to increase low milk supply, you can read BellyBelly’s article: 11 Foods That Improve Breastmilk Production.
Can mothers take metformin while breastfeeding for weight loss?
Sensible ways for breastfeeding mothers to lose weight after giving birth would be to make healthier lifestyle and diet choices as opposed to taking drugs.
As a breastfeeding mother, here are some things you can do:
- Eat a wide variety of healthy, nutrient dense foods
- Stay hydrated
- Engage in gentle exercise that is appropriate to your postpartum stage
- Get enough rest.
Although breastfeeding burns calories, some women find it hard to lose weight while they are breastfeeding. This could be because breastfeeding increases hunger and slows fat metabolism, which is the body’s way of preserving fat reserves for breast milk in adverse conditions.
If you have previously taken metformin for weight loss, talk to your family doctor or another healthcare provider for advice about continuing metformin while breastfeeding for weight loss.
Can breastfeeding mothers use metformin treatment for polycystic ovary syndrome?
Metformin is used in the treatment of polycystic ovary syndrome (PCOS), a hormonal condition that causes cysts to form on the outside of the ovaries.
Women with polycystic ovary syndrome often have insulin resistance, so metformin is used to lower insulin levels. It’s important to check any medications you were previously taking to treat polycystic ovary syndrome are suitable to continue taking while breastfeeding.
Studies have found that exclusive breastfeeding for 6 months can significantly reduce insulin resistance in the postpartum period, which means the amount of medication you need might have changed.
For more information on polycystic ovary syndrome, you can read BellyBelly’s article: PCOS – What Is PCOS? (PolyCystic Ovarian Syndrome).