The association of maternal thyroid function with placental hemodynamics during pregnancy

Abstract

We examined 164 pregnant women who were divided into three groups. Group I included 76 pregnant women (46.4 %) with euthyroid goiter of I–II degree. Group II consisted of 63 pregnant women (38.4 %) with subclini­cal hypothyroidism and diffuse thyroid goiter of I–II degree. Group III was the controls and consisted of 25 (15.2 %) pregnant women without thyroid pathology. The placenta was studied with the characteristics of ultrasound placentography, placental maturation disorders, the area and localization were determined, and pathological changes in the placental tissue were detected. Changes in the systolic-diastolic ratio in the uterine arteries and umbilical cord arteries were assessed, the resistance index in the uterine arteries, the pulsatile index in the fetal aorta and middle cerebral artery were determined using the method of color Doppler mapping of blood flow in the mother-placenta-fetus system. Study of the echographic picture of structural changes in the placenta revealed a significant impairment of its maturation, especially in the group with euthyroidism. Ultrasound screening revealed that in every second pregnant woman with thyroid disease, the condition of the placenta did not correspond to the gestational age, there were swelling, cysts and placental infarctions, a high frequency of diffuse changes in placental tissue, and hyperechogenic inclusions in the amniotic fluid. An increase in the resistance index in the uterine arteries of pregnant women, especially those with subclinical hypothyroidism, is noteworthy. With increasing gestational age, the peripheral resistance of the placental microvasculature increases due to involutional-dystrophic changes and circulatory disorders, which allows us to develop criteria for the prognosis and diagnosis of placental dysfunction, and to prevent perinatal disorders in pregnant women with thyroid disease.

Keywords

• hypothyroidism
• thyroid gland
• pregnancy
• placental dysfunction
• dopplerometry
• placentography