19wks pregnant.on synthroid 50mcg since 2014.ft3 2.4ng/dl(range 2-4.7). tsh 1.8. is ft3 at a lower side?what's pregnancy ranges?feel concerned

Pregnant/synthroid: TSH is fine , and T3 ? is within range-there is variation. What is T4? -as that is used to determine hypothyroidism . Would recheck in 2-4 weeks. You can get additional reassurance from your OB and ask see an endocrinologist. https://www.medscape.com/viewarticle/752878 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625634/ https://www.infantrisk.com/content/hypothyroidism-and-pregnancy