Metformin During Pregnancy and Breastfeeding

Generic Name: Metformin
Indications: Used to treat type 2 or adult-onset diabetes.
FDA Drug Category: B

Summary Recommendations: Metformin is a drug prescribed to help control blood glucose levels in patients with type 2 diabetes. The drug may be combined with other therapies and medications, but it is never prescribed for type 1 diabetes. Patients who become pregnant while taking Metformin should continue taking the medication as prescribed. No risks to pregnancy or fetal health have been reported.

Metformin is also prescribed as Riomet, Fortamet, Glumetza, Glucophage and Glucophage XR.

General Precautions: Patients diagnosed with type 2 diabetes often follow a controlled diet and medication regime to maintain healthy blood glucose levels. If metformin is prescribed and you become pregnant, continue taking your medication and consult your obstetrician about possible risks of taking the drug.

Stopping metformin use abruptly can cause harmful side effects, including a sharp rise in blood glucose. Uncontrolled blood glucose can lead to death. Metformin has been placed in the pregnancy category B by the Food and Drug Administration, which means no negative side effects have been reported with use.

Effects While Trying to Conceive: Diabetes can cause fertility problems, so taking metformin may have a positive impact on fertility. There are no negative fertility implications for men or women associated with metformin use.

Effects on Pregnancy: There does not appear to be any threat associated with taking metformin during pregnancy. Animal studies and human reports have not revealed pregnancy or birth complications or side effects. Changes in the body during pregnancy may require changes to type 2 diabetes medications and dietary control. Patients taking insulin, along with metformin, may have to change insulin dosage or frequency or alter metformin dose as needed to control blood glucose levels.

Keeping blood glucose levels under control during pregnancy is important and metformin is considered a safe and effective drug for use during pregnancy.

Safe During Breastfeeding: Metformin does pass to baby in breast milk, but studies have concluded no negative side effects are associated with long-term use of the drug. The levels of metformin in breast milk stay constant over the course of the day, so scheduling breastfeeding around the times you take your medication is not necessary.

In a clinical study of the impact of metformin on breastfeeding, 78% of women were successful. Difficulty breastfeeding or failure to continue breastfeeding were associated with multiple births, low breast milk production or other infant anomalies – not metformin use.