At 6 weeks pregnant, a TSH of 6.65 indicates hypothyroidism. To prevent complications like miscarriage or developmental issues, you should start Levothyroxine, a synthetic thyroid hormone that is completely safe during pregnancy. Your doctor will monitor your blood levels every 4 weeks to adjust the dose. After delivery, your body's thyroid hormone requirements will decrease. You will likely need to either reduce your dosage or stop the medication entirely. Your doctor will re-check your thyroid levels 6 to 8 weeks postpartum to determine if you need to continue treatment. Please contact your obstetrician immediately to get your prescription.