Fetal Growth Restriction (FGR)

Contributor: Shelley Chapman, MD                                       Date: June 2020

Fetal growth restriction (FGR) occurs in approximately 10% of pregnancies and represents the manifestation of a variety of maternal, fetal and placental conditions. The Society of Maternal Fetal Medicine has made recommendations in their SMFM Consult Series #52: Diagnosis and Management of Fetal Growth Restriction. Knowing that each patient will represent a unique clinical picture, the following guidelines should serve as a starting point for consideration.

1. FGR definition as sonographic estimated fetal weight (EFW) or abdominal circumference (AC) below the 10th percentile for gestational age. (Grade 1B)
2. In determining fetal weight percentiles a population–based fetal growth reference should be used (such as Hadlock).
3. Recommend a detailed obstetric ultrasound examination (CPT code 76811) be performed with early–onset FGR (less than 32 weeks of gestation) via referral to Maternal Fetal Medicine, since up to 20% of cases are associated with fetal or chromosomal abnormalities.
4. Recommend women be offered fetal diagnostic testing via amniocentesis, including chromosomal MicroArray analysis (CMA), when FGR is detected with either a fetal malformation or polyhydramnios, regardless of gestational age. (Grade 1B)
5. Recommend pregnant women be offered prenatal diagnostic testing with CMA when unexplained isolated FGR is diagnosed at less than 32 weeks of gestation. (Grade 1C)
6. Recommend PCR for CMV in women with unexplained FGR who elect diagnostic testing with amniocentesis; however, recommend against screening for toxoplasmosis, rubella, or herpes in patients with FGR in the absence of other risk factors.
7. The management of periviable pregnancies will be individualized in terms of ultrasound follow up and testing based on MFM consultation and shared decision making with the patient.
8. Antenatal testing should not be offered until “potential viability”. The NICU at Prisma Health Upstate recommends at least 23 weeks as a minimum for viability. If patients are admitted for ongoing evaluation, consult NICU attending for patient counseling. Occasionally an outpatient NICU consultation may be required to address timing of hospitalization.
9. Recommend that once FGR is diagnosed in a “viable infant”, umbilical artery Doppler assessment should be performed weekly. The use of ductus venosus or middle cerebral artery Doppler studies for routine clinical management of early or late onset FGR can be individualized. (Grade 2A)
10. If umbilical artery absent end-diastolic velocity (AEDV) is detected, consider admission for continuous electronic fetal monitoring (CEFM), assessment for evolving preeclampsia and antenatal steroids. If stable, then outpatient management can be considered.
11. If reversed end diastolic flow (REDV) is noted in the umbilical cord, admission to the hospital for CEFM, assessment for evolving preeclampsia and antenatal steroids is warranted with anticipation of hospitalization until delivery unless resolution of findings.
12. If delivery is anticipated, recommend magnesium sulfate for neuroprotection if <32 weeks gestation.
13. Weekly cardiotocography (CTG) is recommended for FGR after viability in the absence of AEDF or REDV in the umbilical cord. Thus twice weekly antenatal testing including BPP (complete or modified) with Dopplers in one setting and NST in a second setting is recommended for FGR.
14. Delivery timing:

• 30- 32 weeks gestation for pregnancies with FGR and REDV
• 33- 34 weeks of gestation for pregnancies with FGR and AEDV
• 37 weeks and pregnancies with FGR and umbilical artery Doppler waveform with decreased diastolic flow (S:D > 95%) OR severe FGR with EFW less than the 3rd percentile
• 38-39 weeks of gestation with FGR when EFW is between the third and 10th percentile and the umbilical artery Doppler is normal

15. Antenatal corticosteroids:

• Recommended if delivery anticipated <34 weeks
• Consider for pregnancies between 34 0/7 and 36 0/7 weeks in women without medical complications and no prior course of antenatal corticosteroids.

16. Consider cesarean section for pregnancies with FGR complicated by absent or reversed end-diastolic velocity.

Reference

1. Martin JG, Biggio JR, Abuhamad A. SMFM Consult Series #52; Diagnosis and management of fetal growth restriction. AJOG. DOI:https://doi.org/10.1016/j.ajog.2020.05.010.