Methodology
This prospective cohort study was conducted at the Jawaharlal Institute of Postgraduate Medical Education & Research (JIPMER), Pondicherry, India. JIPMER is a super-specialty tertiary care hospital catering to all populations in the Pondicherry state and the adjacent districts of Tamil Nadu.
The study protocol approval was obtained from the JIPMER Scientific AdvisoryCommittee and the InstituteEthics Committee (Human studies). This study was conducted according to theDeclaration ofHelsinki guidelines. All individuals provided written informed consent.
Participants were recruited from May 2012 to June 2016. A total of 1,931 pregnant women were screened for participation in the outpatient department of Obstetrics and Gynaecology, ofwhich 1,512 were enrolled and consented to participate. Among the consented population, 369 were women with risk for developing PE.Flowchart of the number of patients recruited and analysed is reported in Figure 1.The inclusion criteria of the risk group include any or all of the following characteristics like family h/o PE, PE in a previous pregnancy, body mass index (BMI) >35 Kg/m2, diastolic blood pressure>80 mmHg at the first visit, extremes of reproductive age (18 to 20 years and more than 35 years), Pre-existing medical conditions such as renal disease and chronic hypertension, and multiple gestations (more than two).
We performed a nested case-control study to determine the risk factors for developing PE among high-risk pregnant women. We also included patient characteristics at the time of their first visit during the first trimester. Patient characteristics that were included are demographic characteristics (age, socioeconomic status), medical history (family history of high blood pressure, PE, history of abortion, multiple gestations), and clinical risk factors (maternal blood group, sex of the new-born). There were no missing data on covariates. Study participants were followed till delivery and noted for the development of PE.
Statistical Analysis: To determine the age-specific incidence of PE in the high-risk group we report the number of PE cases to the total number of persons at risk in each age group for the period of study. In the comparison of cases and controls, we first compared patient characteristics before the event using the x2statistic for categorical variables and the Student t- test for continuous variables. We then sought to identify risk factors associated with PE using conditional logistical regression. All the tests for statistical significance were 2-tailed tests and a p-value of <0.05 was considered statistically significant. All statistical analyses were performed using SPSS version 18.