A1C Target in Pregnancy
The A1C target during pregnancy is <6% (42 mmol/mol) if this can be achieved without significant hypoglycemia, but may be relaxed to <7% (53 mmol/mol) if necessary to prevent hypoglycemia. 1
Optimal Target and Rationale
The ideal A1C goal is <6% (42 mmol/mol) throughout pregnancy, as this level is associated with the lowest rates of adverse fetal outcomes including large-for-gestational-age infants, preterm delivery, and preeclampsia. 1, 2
This target is lower than the standard non-pregnant diabetes target because A1C levels are physiologically lower in normal pregnancy due to increased red blood cell turnover, making the normal pregnancy A1C range naturally lower than in non-pregnant individuals. 1
In the second and third trimesters specifically, A1C <6% has been shown to have the lowest risk of macrosomia, preterm delivery, and preeclampsia in observational studies. 1
Individualization Based on Hypoglycemia Risk
If the <6% target cannot be achieved safely without significant hypoglycemia, the target should be relaxed to <7% (53 mmol/mol). 1
This is particularly relevant for women with type 1 diabetes who have a history of recurrent hypoglycemia or hypoglycemia unawareness, as they face greater challenges achieving tight control safely. 1
Hypoglycemia during pregnancy carries additional risks beyond the usual adverse effects, including potential increased risk of low birth weight, making it critical to balance tight control against hypoglycemia risk. 1
Preconception A1C Target
Prior to conception, the A1C target is <7% to minimize the risk of congenital anomalies, spontaneous abortion, and diabetic embryopathy (including anencephaly, microcephaly, and congenital heart disease). 1
Ideally, aim for A1C as close to 6% as possible before conception without causing hypoglycemia. 3
Monitoring Frequency
- A1C should be monitored more frequently during pregnancy than in non-pregnant individuals (e.g., monthly) due to altered red blood cell kinetics and the need for close glycemic surveillance. 1, 2
Important Caveats
A1C should be used as a secondary measure of glycemic control in pregnancy, not the primary metric, because it may not fully capture postprandial hyperglycemia which drives macrosomia. 1
Self-monitoring of blood glucose (fasting and postprandial) remains the primary method for achieving optimal glycemic control during pregnancy. 1, 2
The specific blood glucose targets that should accompany A1C monitoring are: fasting 70-95 mg/dL (3.9-5.3 mmol/L), 1-hour postprandial 110-140 mg/dL (6.1-7.8 mmol/L), or 2-hour postprandial 100-120 mg/dL (5.6-6.7 mmol/L). 1, 2