Types of studies and patients
The eligibility criteria for the inclusion of studies were
predetermined. Observational studies that assessed differences in serum
LDH levels among women with hypertensive disorders of pregnancy
(gestational hypertension, preeclampsia, eclampsia, HELLP syndrome) and
healthy controls were considered eligible for inclusion. Small case
series (<10 patients), case reports, conference proceedings
and animal studies were excluded from the present systematic review.
Studies that involved pregnant women with comorbidities were excluded
from the present systematic review. The control group consisted of
healthy pregnant women, without evidence of any gestational
complication. Studies were not excluded based on preeclampsia
definition, since no date restrictions were applied.