Association of ABO and RhD Blood Types with Thyroid Abnormalities in Pregnant Women

The associations between the blood group system and various diseases have long been investigated since the discovery of blood group antigens. However, up to now, the relationship of ABO and RhD blood types with thyroid abnormalities in pregnant women has not been reported yet. The present study aims to investigate the association of ABO and RhD blood types with thyroid abnormalities in pregnant women in Qingdao, China.

A total of 5,675 pregnant women aged 18 - 50 years old at 7 to 13 weeks of gestation were enrolled into this cross-sectional study. Serum concentrations of free T3 (FT3), free T4 (FT4), thyroid stimulating hormone (TSH), total T3, total T4, thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TGAb), thyrotrophin receptor antibody (TRAb), ferritin (FERR), and vitamin B12 were detected, and blood type identification was performed. The association of ABO and RhD blood types with thyroid abnormalities was evaluated by logistic regression analysis.

Pregnant women with blood type A and B had significantly higher concentrations of TSH than women with blood type O, and FERR and B12 levels were remarkably increased in RhD(+) women than in RhD(-) women. Pregnant women with blood type A were less likely to be TRAb(+), and pregnant women with blood type AB were more likely to suffer from clinical or subclinical hypothyroidism, compared with blood type O. In addition, RhD(+) pregnant women had less likelihood to be TRAb(+) in comparison to RhD(-) women.

Our findings indicate novel meaningful correlations between ABO and RhD blood types and thyroid disorders in pregnant women, which will offer guidance for better screening and management of thyroid function in pregnant women.