Abundance of cord and maternal serum proteins and IgG transfer ratio in a Chinese population: a cross-sectional observational study

There are inter-population differences in the maternal-to-fetal transfer ratio of immunoglobulin G (IgG), and there is currently a lack of research on the Chinese population. In this cross-sectional observational study, the serum concentrations of total protein, albumin, and total IgG in 71 paired samples, and IgG1–4 in 50 paired maternal and cord blood samples, were measured in Chinese mothers who delivered live births at ≥ 37 gestational weeks. The results show cord and maternal serum albumin concentrations were 36.98 ± 3.16 g/L and 36.53 ± 2.33 g/L, respectively ( t = -0.98, P > 0.05). The cord serum total IgG concentration was 9.00 (8.20–9.90) g/L, and the total protein concentration was 55.63 ± 5.30 g/L, whereas the maternal serum total IgG concentration was 10.80 (9.40–11.80) g/L, and the total protein concentration was 65.14 ± 4.57 g/L ( z = -5.38, P < 0.0001; t = 11.45, P < 0.0001). The maternal-to-fetal transfer ratio of total IgG was 0.82 (0.76–0.93), and the hierarchy of the maternal-to-fetal transfer ratios of IgG1–4 was as follows: IgG1 (1.28 ± 0.38) > IgG4 (1.06 ± 0.41) > IgG3 (0.86 ± 0.34) ≥ IgG2 (0.75 ± 0.28). Cord and maternal serum showed similar albumin but lower total protein; IgG1–4 transfer hierarchy matched prior studies, while ratios were lower than in most populations. These findings may help to understand the immune protection mechanisms in newborns among the Chinese population.