Information sources and search methods
Two authors (V.P and M.P.) searched Medline (1966–2021), Scopus (2004–2021), Clinicaltrials.gov (2008–2021), EMBASE (1980-2021), Cochrane Central Register of Controlled Trials CENTRAL (1999-2021) and Google Scholar (2004-2021) along with the reference lists of electronically retrieved full-text papers. The date of the last search was set at March 18, 2021. The search strategy included the text words “lactate dehydrogenase; LDH; preeclampsia; gestational hypertension; HELLP” and is presented in brief in Supplemental Figure 1 .
Studies were selected in three consecutive stages. Following deduplication, the titles and abstracts of all electronic articles were independently screened by three authors (MP, VP and SS) to assess their eligibility. The decision for inclusion of studies in the present meta-analysis was taken after retrieving and reviewing the full version of articles that were considered potentially eligible. Discrepancies that arose in this latter stage were resolved by consensus from all authors.