During pregnancy, it is important to monitor thyroid function as imbalances can affect both the mother and baby. A TSH level of 4.78 may be slightly elevated, indicating subclinical hypothyroidism. It is recommended to consult with your healthcare provider for further evaluation and management. They may suggest additional tests such as free T4 and TPO antibodies to assess thyroid function more comprehensively. Treatment options, if necessary, may include medication adjustments or hormone replacement therapy to ensure optimal thyroid levels throughout pregnancy for the well-being of both you and your baby.