Metformin use during the first trimester of pregnancy. Is it safe?

Title
Metformin use during the first trimester of pregnancy. Is it safe?.
Source
Canadian Family Physician. 52:171-2, 2006 Feb.

"Despite the traditional response that all oral hypoglycemic agents are absolutely contraindicated during pregnancy, evidence that metformin is probably safe during the first trimester of pregnancy and beyond is accumulating. Results of a recent meta-analysis by the Motherisk Program showed no increase in incidence of major malformations and a potential protective effect in this patient population."

Metformin is an oral medication that lowers blood glucose (sugar) and is used for treating type 2 diabetes. Insulin is a hormone produced by the pancreas that lowers glucose levels in blood by reducing the amount of glucose made by the liver and by increasing the removal of glucose from the blood by muscle and fat tissues. Diabetes results because of reduced production of insulin and reduced uptake (and effects) of insulin on the body's tissues. Metformin acts by increasing the sensitivity of liver, muscle, fat, and other tissues to the uptake and effects of insulin. These actions lower the level of sugar in the blood.

Unlike glucose-lowering drugs of the sulfonylurea class, e.g. glyburide (Micronase; Diabeta) or glipizide (Glucotrol), metformin does not increase the concentration of insulin in the blood and, therefore, does not cause excessively low blood glucose levels (hypoglycemia) when used alone. In scientific studies, metformin reduced the complications of diabetes such as heart disease, blindness and kidney disease. Metformin was approved by the FDA in December of 1994.