2.1 Study Design and Participants
A prospective, observational cohort study was performed between January 2017 and March 2018 at a public tertiary health center (Hospital Sótero del Río, in Santiago, Chile). Women with a singleton pregnancy less than 14 weeks of gestation and with confirmed fetal viability were invited to participate in the study. Patients under the age of 18 or with an intention of delivery at other medical centers were excluded from the present research. Patients with incomplete follow-up until delivery or with an unsatisfactory periodontological evaluation or GCF-PLAP measurements were also excluded from participation. The study was approved by the Scientific and Ethical Review Boards of the Hospital Sótero del Río and the Universidad de Los Andes, and all patients read and signed a written informed consent form prior to sampling and evaluation.
A full periodontal evaluation was scheduled between 11 and 13 6/7 weeks of pregnancy. One dentist, specially trained for this study, evaluated all participants and recorded a detailed maternal and obstetric history. Maternal systolic, diastolic, and mean arterial blood pressure, weight, and height were measured with standardized instruments. A full periodontal diagnostic evaluation was performed, and GCF samples were collected to assess concentrations of PLAP, using a standardized sampling procedure. A plasma sample was obtained from 80 randomly selected women to compare to paired plasma and GCF-PLAP concentrations. Patients, researchers, and health-care providers remained blinded to the results of GCF and plasma PLAP determinations.
After this initial periodontal evaluation, patients received standard obstetrical care, and cases with subsequent obstetrical complications were managed according to local hospital protocols. Patients were followed until delivery and immediate postpartum, with special emphasis on patients who developed gestational hypertension and PE. Data regarding pregnancy outcomes were recorded shortly after delivery in a pre-specified database.