Final answer:
The maternal HbA1c level that leads to a 12-fold increase in the risk of major fetal malformations is 8%.
Step-by-step explanation:
The maternal HbA1c level that leads to a 12-fold increase in the risk of major fetal malformations is 8%.
HbA1c is a measure of the average blood glucose level over the past 4 months, and a level above 12% indicates very poor control of diabetes. Maintaining a HbA1c level close to 7% is recommended for diabetics to prevent complications. Therefore, an HbA1c level of 8% or higher significantly increases the risk of major fetal malformations.