A 29-year-old woman, who is 8 weeks pregnant, presents to the obstetrics clinic for her first prenatal visit. She has a history of hypothyroidism diagnosed three years ago and has been on levothyroxine 100 mcg daily. She confirms adherence to her medication. Laboratory tests reveal a TSH level of 4.8 mIU/L (reference range for pregnancy: 0.1–2.5 mIU/L in the first trimester) with normal free T4 levels. Which of the following is the next step in the management of her hypothyroidism during pregnancy?
