Objectives Preeclampsia is the leading cause of maternal and neonatal morbidity and mortality with incompletely understood pathogenesis. The purpose of the current study is to determine whether there is a relationship between the presence of autoantibody against M2-muscarinic receptor and severe preeclampsia.
Methods Peptide corresponding to amino acid sequences of the second extracellular loops of M2 receptor was synthesised as antigens to test 60 patients with severe preeclampsia, 60 normal pregnant women and 40 non-pregnant controls for the presence of autoantibody using enzyme-linked immunosorbent assay.
Results The frequencies for autoantibody against M2 receptor was 31.7% (19/60) in severe preeclampsia patients, while it was 10.0% (6/60) (p = 0.006) in normal pregnant women and 8.3% (5/60) (p = 0.002) in non-pregnant controls. The geometric mean titer of autoantibody was also increased in severe preeclampsia patients. By logistic regression analysis, positivity for autoantibody against M2 receptor was associated with fetal distress (OR, 22.4; 95% CI, 4.4-114.5; p < 0.001), preterm birth (OR, 4.0, 95%CI, 1.6-10.0; p = 0.003), neonatal asphyxia (OR, 9.0; 95% CI, 2.5-32.3; p = 0.001), long-term neonatal hospitalisation (OR, 3.5; 95% CI, 1.4-8.7; p = 0.007), and perinatal death (OR, 18.47; 95% CI, 3.6-96.2; p = 0.001).
Conclusions This novel pilot study demonstrated for the first time that the presence of autoantibody against M2 receptor is increased in patients with severe preeclampsia. Pregnant women who are positive for autoantibody against M2 receptor are at increased risks of neonatal mortality and morbidity. We posit that autoantibody against M2 receptor may be involved in the pathogenesis of severe preeclampsia.