Study Population is clearly defined Inclusion criteria are clearly stated Exclusion criteria are clearly stated PE vs CTR matched or P>.05 for maternal characteristics PE vs CTR matched or P>.05 for gestational age PE vs CTR matched or P>.05 for birth weight Statistical methods Statement of diagnostic criteria for PE (exposure) Measurement of epigenetic change conducted (outcome) Were results adjusted and controlled for confounders? Limitations of experimental study identified Total score Bai [35] 1 1 1 2 1 0 1 1 1 0 1 10 Czikk [26] 1 1 1 2 0 0 1 1 1 1 1 10 Gao [36] 1 1 1 2 1 0 1 1 1 0 1 10 Hu [24] 1 1 1 2 1 1 1 1 1 0 1 11 Li [23] 1 1 1 2 1 1 1 1 1 0 0 10 Muralimanoharan [25] 1 1 0 2 1 1 1 1 1 0 1 10 Xiang [37] 1 1 1 2 0 0 1 1 1 1 1 10 Yan [38] 1 1 1 2 1 0 1 1 1 0 1 10 Yuen [39] 1 1 1 1 1 1 1 1 1 0 1 10 Zhu [22] 1 1 0 2 1 1 1 1 1 1 1 11 PE: Preeclampsia; CTR: Control

Table 2: Quality scores of included studies.