High Body Mass Index Is an Indicator of Maternal Hypothyroidism, Hypothyroxinemia, and Thyroid-Peroxidase Antibody Positivity during Early Pregnancy

Abstract

Background. Maternal thyroid dysfunction in early pregnancy may increase the risk of adverse pregnancy complications and neurocognitive deficiencies in the developing fetus. Currently, some researchers demonstrated that body mass index (BMI) is associated with thyroid function in nonpregnant population. Hence, the American Thyroid Association recommended screening thyroid function in obese pregnant women; however, the evidence for this is weak. For this purpose, our study investigated the relationship between high BMI and thyroid functions during early pregnancy in Liaoning province, an iodine-sufficient region of China. Methods. Serum thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid-peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb) concentration, urinary iodine concentration (UIC), and BMI were determined in 6303 pregnant women. Results. BMI ≥ 25 kg/m2 may act as an indicator of hypothyroxinemia and TPOAb positivity and BMI ≥ 30 kg/m2 was associated with increases in the odds of hypothyroidism, hypothyroxinemia, and TPOAb positivity. The prevalence of isolated hypothyroxinemia increased among pregnant women with BMI > 24 kg/m2. Conclusions. High BMI during early pregnancy may be an indicator of maternal thyroid dysfunction; for Asian women whose BMI > 24 kg/m2 and who are within 8 weeks of pregnancy, thyroid functions should be assessed especially.

Comparison of thyroglobulin and thyroid peroxidase antibodies measured by five different kits in autoimmune thyroid diseases

“…Therefore, we searched for recent reports on screening studies of TgAb and TPOAb. To avoid the influence of diseases themselves, we only considered studies done on healthy control subjects in various regions in different countries [24][25][26][27][28][29][30][31][32][33][34][35][36][37]. In healthy subjects, the incidence of positive TgAb or TPOAb is …”

MANAGEMENT OF ENDOCRINE DISEASE: Isolated maternal hypothyroxinemia during pregnancy: knowns and unknowns

“…Obesity has also been recently associated with low FT 4 levels, through mechanisms that are incompletely understood (33,35,48,49,50 (33). One hypothesis regarding these findings, based on the increase in T 3 seen in association with the low T 4 , is that in obesity, there is increased peripheral deiodination (52), as leptin, produced by adipose tissue, is known to stimulate T 4 to T 3 conversion (53,54).…”

Early pregnancy thyroid hormone reference ranges in Chilean women: the influence of body mass index

“…It is known that TSH and body mass index (BMI) are positively correlated in nonpregnant subjects . Free T4 concentrations have also been shown to change with increasing BMI . In 2011, the American Thyroid Association (ATA) guidelines suggested that “serum TSH testing should be carried out in pregnant women with morbid obesity”, but there were insufficient data on the relationship between BMI and maternal thyroid function during early pregnancy to routinely consider BMI as a variable when establishing normal TSH values.…”