Material and method
In this study the secondary analysis of the data from analytical prospective study conducted from September 2019 to April 2022 after approval from the institutional ethical committee was done. All antenatal high risk women with gestational age between 20-22 weeks were included; the gestational age was calculated from the first-trimester ultrasound. The antenatal women were adjudged as high risk for preeclampsia based on the presence of one or more risk factors, namely, nulliparity; pre-pregnancy or first-trimester body mass index (BMI) of 30 Kg/M2 or more; maternal age either 35 years or older; use of assisted reproductive technology for conception or family history of hypertension; previous pregnancy more than ten years ago or the presence of one or more major risk factors such as preeclampsia in previous pregnancy; chronic hypertension; diabetes mellites; or chronic kidney disease 7. Those with multiple pregnancies were excluded from the study. The blood pressure was measured in one arm, and two recordings were made at the one-minute interval. The final BP measurement (average of the two measurements) was used to calculate mean arterial pressure (MAP). The women underwent transabdominal ultrasonography (Aloka Prosound alpha 6) for the uterine artery Doppler measurement. It was identified as an aliasing vessel perpendicular to the internal iliac vessel, atleast four even waveforms were considered good image; both right and left uterine vessels were measured and the mean value was taken.
For the measurement of serum sFLT-1 and PlGF, three ml of venous blood was drawn by venepuncture into non-heparinized tubes. The blood samples were allowed to clot for 15–20 min and centrifuged at 1500 rpm for 5 min. The serum was removed, and aliquots were stored at -20°C. The biomarkers were measured by fully automated equipment using electro-chemiluminescence technology on the Roche platform (cobas e 411). the biomarkers were repeated at 28-30 weeks, and 34-36 weeks of gestation.
The antenatal check-up was done regularly at four-week intervals till 28 weeks, then two weekly till 36 weeks, and weekly thereafter. Investigations such as liver function tests, kidney function tests, fundus examination, peripheral smear, and complete blood count were done as and when required. Intergrowth 21 growth charts were used for the estimation of fetal weight centiles 8. FGR was defined as an estimated fetal weight (EFW) less than the 3rd centile, or EFW less than 10th centile plus abnormal fetal Doppler (PI more than 95th centile in the umbilical artery, PI less than 5thcentile in the middle cerebral artery, or cerebroplacental ratio less than 5thcentile) on antenatal ultrasound 9. The delivery details, the newborn’s condition at delivery, and that of the mother were noted. The women and babies were followed for one week following delivery.
The data entry was done in the Microsoft EXCEL spreadsheet, and the final analysis was done using Statistical Package for Social Sciences (SPSS) software, IBM manufacturer, Chicago, USA, version 21.0. For statistical significance, the p value of less than 0.05 was considered statistically significant. The association of the variables which were quantitative and not normally distributed in nature was analyzed using the Mann-Whitney test. The Receiver operating characteristic curve (ROC) was used to find the cut-off of PlGF. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.