**Core Concept**
Glycosylated hemoglobin (HbA1c) is a measure of average blood glucose levels over the past 2-3 months, reflecting long-term glycemic control. In pregnancy, tight glucose control is crucial to prevent complications such as macrosomia, polyhydramnios, and increased risk of cesarean delivery.

**Why the Correct Answer is Right**
During pregnancy, the glucose tolerance is decreased due to insulin resistance and increased insulin production. However, the normal range for HbA1c in pregnancy is slightly higher than in non-pregnant individuals. The American College of Obstetricians and Gynecologists (ACOG) recommends that HbA1c levels should be less than 6.5% in pregnant women. This is because higher levels of HbA1c are associated with an increased risk of maternal and fetal complications.

**Why Each Wrong Option is Incorrect**
**Option A:** 5.5% - This is too low and does not account for the physiological changes that occur during pregnancy.
**Option B:** 7% - This is too high and may indicate poor glycemic control, increasing the risk of complications.
**Option C:** 6% - While close, this is still slightly above the recommended threshold.

**Clinical Pearl / High-Yield Fact**
In pregnancy, the HbA1c level should be interpreted in the context of the patient's individual glucose tolerance and risk factors.

**Correct Answer: C. 6%**