METHODS
This was an observational retrospective study conducted at Vall d’Hebron Barcelona Hospital Campus, Barcelona, Spain. This study was approved by the Vall d’Hebron Barcelona Hospital Campus Ethics Committee (PR[AMI]556/2021) on 5th November 2021. For the study group, inclusion criteria were women (a) attending our site with confirmed SARS-CoV-2 infection at any point during pregnancy and (b) undergoing the first-trimester combined screening for PE. The recruitment period for the SARS-CoV-2 group was from February 2020 to September 2021. Our centre was a referral hospital for severe COVID-19 pneumonia, especially during pregnancy; therefore, cases were both patients from our area and patients referred from all across Catalonia. For the population group, data was obtained from general population attending first-trimester screening for PE in 6 centres across Catalonia (Vall d’Hebron Barcelona Hospital Campus, Hospital Universitari Germans Trias i Pujol, Hospital Universitari de Tarragona Joan XXIII, Hospital Universitari Mútua Terrassa, Consorci Sanitari de Terrassa, Hospital Universitari de Girona Doctor Josep Trueta) between May 2019 and June 2021. A previous study assessing the screening performance of the first-trimester screening for PE was approved (PR(AMI)147/2021), and, therefore, data from general population was prospectively recorded.
SARS-CoV-2 infection was confirmed either by real-time polymerase chain reaction (RT-PCR) or an antigen test. Several changes in screening protocols have occurred during the study period, while scientific evidence or assistance care needs were changing. Therefore, our study population included both patients systematically screened at hospital admission and patients screened because of symptomatology or close contact. In the study group, severity of the symptoms was the criteria used for classification: mild forms of COVID-19, including asymptomatic and symptomatic women not requiring hospitalization, and severe forms of COVID-19, including patients requiring hospitalization due to severe pneumonia.
In Catalonia, the first-trimester screening for PE is routinely performed during the first-trimester scan between 11+0 and 13+6 weeks of gestation. Gestational age is confirmed by fetal crown-rump length measurement during this scan11. Demographic characteristics, obstetric history, maternal history and biophysical and biochemical markers are documented in the clinical records. Biophysical markers, including transabdominal mean uterine artery pulsatility index (UtAPI) and mean arterial blood pressure (MAP), are assessed during the first-trimester scan. Biochemical markers, including serum pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF), are measured at the routine first-trimester blood test (from 8+0 to 13+6 weeks of gestation). Maternal serum PAPP-A and PlGF levels were determined by the fully automated Elecsys assays for PAPP-A and PlGF on an immunoassay platform (cobas e analysers; Roche® Diagnostics, Rotkreuz, Switzerland). First-trimester risk for PE was then calculated4. High risk for PE was defined as a risk for early-onset PE ≥ 1/170. This cut-off value provides a 90.9% detection rate for early-onset PE at a 12.7% false-positive rate12.
All examiners were certified by the Fetal Medicine Foundation for PE risk assessment and Doppler ultrasound assessment.