BACKGROUND AND PURPOSE:

• FGR is defined as EFW <10th percentile
• SGA is defined as BW below < 10th percentile for gestational age
• There is limited data on early onset FGR, especially severe FGR, defined as <5 percentile
• Zhang-Rutledge et al. (Journal of Ultrasound in Medicine, 2018) assessed whether severity of fetal growth restriction impacted neonatal and pregnancy outcomes

METHODS:

• Retrospective cohort study
  • Singleton and nonanomalous
  • EFW ≤10th percentile at 18 to 24 weeks’ gestation
• The cohort was divided into fetuses with estimated fetal weight
  • <5th percentile
  • Between the 5th to 10th percentiles
• Ultrasound
  • Measurements based on Hadlock
  • Midgestation: 18w0d-24w6d
• FGR protocol
  • Serial growth scans every 3 to 4 weeks
  • EFW <10th percentile: Weekly antenatal testing at 32 weeks’ gestation
  • EFW <5th percentile: Weekly antenatal testing at 28 weeks
  • Abnormal umbilical artery Doppler: Antenatal testing is increased to twice weekly
  • Delivery based on NICHD/SMFM guidelines
• Primary outcome
  • Whether early-onset severe FGR is associated with SGA compared to fetuses measuring in the 5th to 10th percentiles
• Secondary outcomes
  • Compare groups for differences in maternal and neonatal complications

RESULTS:

• 254 FGR fetuses
  • Overall incidence of midgestational FGR in the study population was 2.5%
  • Severe FGR: 91
  • 5th to 10th percentiles: 163
• Fetuses with severe FGR were more likely to be born SGA vs 5th to 10th percentiles
  • Relative risk (RR) 2.82 (95% CI, 1.52-5.23; P = .001)
• Fetuses with severe FGR, compared to 5th to 10th percentiles had higher rates of
  • Hypertensive disorders of pregnancy (RR 1.79; P = .04)
    • 22% vs 12.3%
  • Abnormal umbilical artery Doppler waveforms (RR 6.27; P = .01)
    • 7.7% vs 1.2%
  • Labor induction (RR 1.45; P = .002)
    • 65.9% vs 45.4%
  • Neonatal intensive care unit admission (RR 1.73; P = .02)
    • 28.5% vs 16.6%
  • Apgar scores of less than 7 at 1 minute (RR 2.05; P = .04) but not significantly different at 5 minutes

CONCLUSION:

• The authors suggested that severe FGR at midgestation may be more reflective of pathologic restriction vs constitutional restriction while those fetuses between the 5th and 10th percentile may be constitutionally small with less risk to the pregnancy
• Different management algorithms for serial surveillance may be indicated

Learn More – Primary Sources:

Significance and Outcomes of Fetal Growth Restriction Below the 5th Percentile Compared to the 5th to 10th Percentiles on Midgestation Growth Ultrasonography

Related ObG Topics:

Does Maternal Depression or Stress Affect Fetal Growth?

Cesarean or Vaginal Delivery for Preterm Fetal Growth Restriction?

RCOG or ACOG for Predicting Small for Gestational Age Birth?