Serum Beta-2-microglobulin levels in intrauterine growth-restricted and normal pregnancies

Objective: It was the aim of this study to investigate circulating levels of beta(2)-microglobulin (a marker of renal function) in mothers and fetuses/neonates from intrauterine growth-restricted (IUGR, characterized by impaired nephrogenesis) and appropriate for gestational age (AGA) pregnancies.

Methods: Serum beta(2)-microglobulin levels were determined in 40 parturients and their 20 IUGR and 20 AGA fetuses/neonates on postnatal days 1 (N1) and 4 (N4). Comparatively, creatinine concentrations were measured.

Results: No significant differences in beta(2)-microglobulin levels were observed between the 2 groups. In both groups, maternal serum beta(2)-microglobulin levels were significantly lower than fetal, N1 and N4 levels (in all cases p < 0.001 in the AGA group and p <or= 0.002 in the IUGR group). In the AGA and IUGR groups, N4 beta(2)-microglobulin levels were significantly elevated compared with fetal (p = 0.004 and p = 0.001, respectively) and N1 levels (p = 0.002 and p = 0.001, respectively). In both groups, maternal and fetal beta(2)-microglobulin levels did not correlate, but beta(2)-microglobulin and creatinine levels positively correlated in maternal and neonatal samples (in all cases r >or= 0.342 and p <or= 0.031).

Conclusions: Serum beta(2)-microglobulin levels do not differ between IUGR and AGA groups, significantly increase after birth and are not associated with gender or gestational age. Furthermore, maternal levels do not correlate with fetal levels, implying the presence of a placental barrier.