CD40LG and cytomegalovirus infection: The results of meta-analysis based on PCR (OR: 3.09; 95% CI:0.72–13.24; I2=57.3%), IgG-ELISA (OR: 1.24; 95% CI:0.83–1.85; I2=71%) and IgM-ELISA (OR: 1.04; 95% CI:0.66–1.65; I2=0.0%) demonstrated that CMV infection could not be the potential risk factor for PE (figure 2, A-C).