Perinatal Outcomes of Fetal Growth Restriction, Classified According to the Delphi Consensus Definition: A Prospective Observational Study

Fetal Growth Restriction has been redefined on the basis of biometry (Abdominal Circumference/Estimated Fetal Weight) beyond the original definition of failure of a fetus to reach its full growth potential irrespective of its size. The Delphi consensus has standardised the definition of early and late onset FGR using size (biometry) as well as functional parameters (doppler blood flow). The clinical validity of this consensus in terms of perinatal outcomes has yet to be tested. The aim of the study was to assess and compare the incidence and perinatal outcomes of fetal growth restriction classified by the Delphi consensus as against conventional definitions. This was a prospective cohort study of 500 consecutive patients from February 2018 onwards, in a tertiary hospital (Sir Ganga Ram Hospital, New Delhi) with a fully equipped neonatal intensive care unit. 70 patients were excluded by predefined exclusion criteria. 430 subjects were enrolled as the study population. Enrolled subjects, apart from a dating scan at first visit and an anomaly scan in the 2nd trimester had a transabdominal scan using a 5 MHz curvilinear probe for fetal assessment between 26 and 32 weeks with at least one scan at 31-32 weeks to identify early onset FGR. A repeat USG between 35 and 36 weeks was conducted to identify late onset FGR. All recruited subjects were categorised as Conventional FGR i.e. AC/EFW < 10th% ile (C), early onset (C1) and late onset (C2), Delphi defined FGR (D) based on Delphi Consensus criteria, early onset (D1) and late onset (D2), Non Delphi Conventional FGR as (C-D), early onset (C1-D1) and late onset (C2-D2). Rest of the fetuses were designated as Non FGR (> 10th% ile). The association of incidence along with perinatal outcomes in each group were compared. The incidence of FGR was as follows: conventional criteria: 35.8%, Delphi criteria: 22.7% and Non Delphi Conventional FGR: 13.1%. Delphi defined FGR had statistically significant increased incidence of PPHTN, hypoglycemia and NICU admission in comparison to Conventional FGR. Delphi defined FGR also had statistically significant increased frequency of Apgar < 7, PPHTN, hypoglycemia, seizures, NICU admissions and prolonged stay as compared to Non Delphi Conventional FGR group. Comparing Non FGR fetuses with Non Delphi Conventional FGR fetuses, neonatal outcomes were similar in both groups. Delphi defined FGR is associated with increased frequency of adverse perinatal outcomes as compared to conventionally defined FGR. Delphi defined criteria, should be routinely applied to a fetus who is small (AC/EFW < 10th% ile). This will timely identify a truly growth restricted fetus, who is at risk for adverse perinatal outcome and save the rest from unnecessary monitoring and intervention. The findings of our study call for larger studies validating the use of Delphi consensus in clinical practise.