Changes of serum immunoglobulin level in healthy pregnant women and establishment of its reference interval

Pregnant women in a special physiological period, the body's blood indicators will change to a certain extent. This study aims to explore the changes of serum immunoglobulin levels in healthy pregnant women and establish its reference interval (RI).

A total of 369 healthy pregnant women, who underwent pregnancy examination in the Department of Obstetrics, Second Xiangya Hospital of Central South University from August 2019 to October 2019, were enrolled for this study. They were divided into an early pregnancy group, a middle pregnancy group, and a late pregnancy group according to the pregnancy period, and 123 healthy non-pregnant women were selected as the controls. The levels of immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) were determined by immune transmission turbidities. The level of immunoglobulin E (IgE) was determined by electrochemiluminescence. The differences in immunoglobulin levels between pregnant women and non-pregnant women and among different gestational periods were analyzed, and the RI of serum immunoglobulin level during pregnancy was established.

Compared to the non-pregnant women, the levels of serum IgG, IgM, IgA, and IgE in pregnant women were significantly decreased (all P<0.01), with 51.81% for IgG, 43.84% for IgM, 55.80% for IgA, and 49.80% for IgE. Except that the IgG level of late pregnancy group was significantly lower than that of early pregnancy group (P<0.05), there were no significant differences in the IgG, IgM, IgA, and IgE levels among the other groups (all P>0.05). The RIs of serum IgG in early pregnancy, middle pregnancy, and late pregnancy were 6.02-7.70 g/L, 5.18-6.85 g/L, and 4.58-5.72 g/L, respectively, while the RIs of serum IgM, IgA, and IgE were 0.71-0.93 g/L, 0.90-1.09 g/L, and 68.30-107.69 ng/mL, respectively in pregnant women.

The levels of immunoglobulin in pregnant women are decreased significantly. The establishment of RIs of IgG, IgM, IgA and IgE in healthy pregnant women could provide scientific basis for clinical decision-making.