This paper provides a synopsis of maternal and fetal thyroid hormone stimulation during pregnancy. Treatment of thyroid illness during pregnancy is critical for avoiding negative maternal and fetal outcomes. Thyroid disorders are frequently asymptomatic and difficult to detect without specialized monitoring programs. Even mild maternal thyroid hormone insufficiency can result in fetal neurodevelopment difficulties. The thyroid is over-stimulated during pregnancy, resulting in alterations in thyroid hormone concentrations. Accurate thyroid function testing during pregnancy is crucial for both initiating thyroid hormone therapy and adjusting thyroid hormone dose in people who are already on thyroid hormone. Trimester-specific intervals are particularly critical during pregnancy, when thyroid insufficiency has been linked to poor obstetric outcomes and neuro-developmental impairments in the fetus. Knowing the natural changes in hormone concentrations that occur throughout pregnancy allows for customized supplementation of iodine when needed.