Ultrasound Assessment of Effect of Maternal Thyroid Function During Pregnancy on Fetal and Neonatal Bone Development

Throughout pregnancy, maternal thyroid-related hormones are transported to the fetus via the placenta to allow normal fetal growth and development and are particularly important in the first and second trimesters of pregnancy. During maternal-fetal transport, in addition to thyroid-related hormones, thyroid-stimulating hormone receptor antibodies and antithyroid drugs can enter the fetus and interfere with development of the fetal thyroid gland and endocrine function, potentially leading to hyperthyroidism or hypothyroidism in the fetus or newborn. Several basic studies have been performed to demonstrate the important role of thyroid-related hormones in fetal and neonatal bone development. Ultrasound can assess neonatal skeletal maturity and bone development safely, rapidly, and effectively. This review aims to communicate the latest knowledge about maternal and fetal thyroid function in both normal and pathological pregnancies and summarize the latest advances in the potential effects of abnormal maternal thyroid function on bone development in the fetus and neonate. Finally, it discusses recent advances in research on ultrasound in the assessment of fetal and neonatal bone development.