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Performance of a risk factor-based approach in the detection of small for gestational age neonates: A cohort study
Anna Wan1, Christopher Zampogna1, Maya Reddy1,2
1Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia.
Insights
Antenatal screening for small for gestational age (SGA) infants in Australia is suboptimal, detecting only 39.6% of cases. While most pregnancies have risk factors, fetal growth ultrasounds may be underutilized, impacting early detection and intervention.
Area of Science:
- Obstetrics and Gynecology
- Neonatal Health
- Diagnostic Accuracy Studies
Background:
- Antenatal detection of fetal growth restriction (FGR) is crucial for timely intervention.
- Current Australian standard of care involves risk factor screening and selective ultrasonography for small for gestational age (SGA) detection.
- Evidence on the performance of this screening approach is limited.
Purpose of the Study:
- To evaluate the diagnostic performance of a risk factor-based screening protocol for detecting SGA neonates.
- To determine the detection and false-positive rates of the current antenatal screening method.
Main Methods:
- Retrospective cohort study of singleton deliveries (≥20 weeks gestation) from July 2016 to December 2017.
- SGA defined as birthweight below the tenth percentile using Australian reference ranges.
- Antenatal detection criteria included estimated fetal weight, abdominal circumference below the tenth percentile, or abnormal symphysio-fundal height.
Main Results:
- 13,384 pregnancies were analyzed; 10.0% of infants were SGA.
- The antenatal detection rate for SGA neonates was 39.6% (95% CI 37.0-42.3%).
- The false-positive rate was 10.2% (95% CI 9.6-10.7%), with 77.0% of pregnancies having at least one SGA risk factor.
Conclusions:
- The current risk factor-based screening protocol demonstrates suboptimal antenatal recognition of FGR.
- A significant proportion of pregnancies (77.0%) present with risk factors for SGA infants.
- There is a potential underutilization of fetal growth ultrasonography in pregnancies with identified risk factors.
Background:
Antenatal detection of fetal growth restriction allows the opportunity to increase surveillance and initiate intervention to prevent adverse outcomes. Detection of small for gestational age (SGA) fetuses with risk factor screening and selective ultrasonography is the standard of care in Australia, but evidence regarding performance is lacking.
Aims:
To evaluate the diagnostic performance of a risk factor-based screening approach in detection of SGA neonates.
Materials And Methods:
Retrospective cohort study conducted in a metropolitan maternity service, including all consecutive singleton deliveries over 20 weeks gestation from July 2016 to December 2017, and excluding terminations of pregnancy. An SGA neonate was defined by birthweight below the tenth percentile according to Australian reference ranges. Antenatally detected SGA cases were defined by estimated fetal weight or abdominal circumference below the tenth percentile for gestational age, or abnormal symphysio-fundal height. The diagnostic accuracy of the screening protocol was calculated using detection rates and false-positive rates.
Results:
There were 13 384 singleton pregnancies included. There were 1330 infants (10.0%) who were SGA at birth. Antenatal detection rate of SGA neonates was 39.6% (95% confidence interval (CI) 37.0-42.3%), with a false-positive rate of 10.2% (95% CI 9.6-10.7%). There were 10 266 pregnancies (77.0%) which had at least one risk factor for an SGA infant. Of these, 6650 (64.8%) underwent at least one fetal growth ultrasound after 24 weeks gestation.
Conclusions:
Antenatal recognition of poor fetal growth is suboptimal using our current screening protocol. Three-quarters of pregnancies demonstrated risk factors for delivering an SGA infant, but growth ultrasonography may be underutilised.
