Pregnancy: Uncontrolled diabetes during pregnancy (gestational or permanent) is associated with increased risk of congenital abnormalities and perinatal mortality.
A limited amount of data from the use of Metformin in pregnant women does not indicate an increased risk of congenital abnormalities. Animal studies do not indicate harmful effects with respect to pregnancy, embryonic or fetal development, parturition or postnatal development (see Pharmacology: Toxicology: Preclinical Safety Data under Actions).
However, when the patient plans to become pregnant and during pregnancy, diabetes should not be treated with Metformin but Insulin should be used to maintain blood glucose levels as close to normal as possible in order to lower the risk of fetal malformations associated with abnormal blood glucose levels.
Lactation: Metformin is excreted into human breast milk. No adverse effects were observed in breastfed newborns/infants. However, as only limited data are available, breastfeeding is not recommended during Metformin treatment. A decision should be made whether to discontinue breast-feeding or to discontinue Metformin, taking into account the benefit of breast-feeding and the potential risk to adverse effect in the infant.