top of page



You can still breastfeed if you have had gastric bypass surgery. You will need to be extra careful about making sure you are getting enough nutrition. Your body will provide any nutrients that are in short supply to your breastmilk first, and then to your body. It is important that you tell your baby’s healthcare provider about your history so that they can watch him carefully for any signs of not getting the proper nutrition.


Gastric bypass surgery is performed to help you lose weight and lower your risk of serious health conditions such as diabetes, high blood pressure, heart disease and stroke. The surgery helps you lose weight by changing how your stomach and small intestine handle the food you eat. After surgery your stomach is smaller and you feel full with less food: this decreases the number of calories that you take in each day and helps you lose weight, but it also affects your body’s ability to absorb some important nutrients.


There are many different types of gastric bypass surgery, resulting in different levels of nutrient absorption. If you have had gastric bypass surgery you may be at risk for vitamin B12, calcium, folate, iron and protein deficiencies, and you may need to take supplements to ensure your breastmilk is fully nutritious. The Womanly Art of Breastfeeding advises that it’s “also important to investigate and treat any underlying causes of obesity, such as polycystic ovary syndrome (PCOS), insulin resistance, or thyroid problems, any of which can decrease milk production.”


According to Nutrition During Lactation (Hamosh 1991, p. 157-58), a full-term infant of a well-nourished mother will be born with a store of vitamin B12 sufficient to meet his needs for about 8 months. If the mother is not vitamin B12 deficient herself, then her milk is an excellent source of vitamin B12 and is more than sufficient for her baby’s needs through the first year. There is evidence that babies born to vitamin B12 deficient mothers have low stores of vitamin B12 at birth. Studies have shown that mothers who are vitamin B12 deficient have low levels of vitamin B12 in their milk.


Breastfed infants may develop clinical signs of vitamin B12 deficiency before their mothers do. Vitamin B12 deficiency may develop in the breastfed infant by 2 – 6 months of age, but may not be clinically apparent until 6 – 12 months. Signs and symptoms of vitamin B12 deficiency in infants include vomiting, lethargy, anemia, failure to thrive, hypotonia (low muscle tone), and developmental delay/regression.


If your baby’s healthcare provider determines that your baby is not getting enough of certain nutrients talk to them about your options.


You might find our book Feed Yourself, Feed Your Family useful.



Clinical Lactation 6(4), 2015, pp. 144-152, “Breastfeeding Outcomes Following Bariatric Surgery” by Caplinger, P, et al.CBI MSF-29663.

Maternal and Child Nutrition, Volume 6, Supplement 2, October 2010, pp. 39-54(16): Nutritional requirements during lactation by Victoria Hall Moran et al.

*Parts of the contents of this page was generously supplied by La Leche League International

bottom of page