SMFM Consult Series #52: Diagnosis and Management of Fetal Growth Restriction
Fetal growth restriction (FGR) is the final manifestation of a variety of maternal, fetal, and placental conditions. Fetal growth restriction occurs in up to 10% of pregnancies and is second to premature birth as a cause of infant morbidity and mortality. In addition to its significant perinatal impact, FGR also has an impact on long-term health outcomes. Fetal growth restriction remains a complex obstetric problem with disparate published diagnostic criteria, poor detection rates, and limited preventative and treatment options. The purpose of this document is to outline an evidence-based, standardized approach for the prenatal diagnosis and management of FGR. The following are Society for Maternal-Fetal Medicine (SMFM) recommendations: (1) we recommend that FGR be defined as a sonographic estimated fetal weight (EFW) or abdominal circumference (AC) below the 10th percentile for gestational age (GRADE 1B); (2) we recommend the use of population-based fetal growth references (such as Hadlock) in determining fetal weight percentiles (GRADE 1B); (3) we recommend against the use of low- molecular-weight heparin for the sole indication of prevention of recurrent FGR (GRADE 1B) and (4) we recommend against the use of sildenafil or activity restriction for in-utero treatment of FGR (GRADE 1B); (5) we recommend that a detailed obstetric ultrasound examination (CPT code 76811) be performed with early-onset FGR (less than 32 weeks of gestation) since up to 20% of cases are associated with fetal or chromosomal abnormalities (GRADE 1B); (6) we recommend that women be offered fetal diagnostic testing, including chromosomal microarray analysis (CMA), when FGR is detected and a fetal malformation, polyhydramnios, or both are also present, regardless of gestational age (GRADE 1B); (7) we recommend that pregnant women be offered prenatal diagnostic testing with CMA when unexplained isolated FGR is diagnosed at less than 32 weeks of gestation (GRADE 1C); (8) we recommend against screening for toxoplasmosis, rubella, or herpes in pregnancies with FGR in the absence of other risk factors and recommend polymerase chain reaction (PCR) for CMV in women with unexplained FGR who elect diagnostic testing with amniocentesis (GRADE 1C); (9) we recommend that once FGR is diagnosed, umbilical artery Doppler assessment should be performed every 1 to 2 weeks to assess for deterioration (GRADE 1C); (10) with decreased end-diastolic velocity, ie, flow ratios greater than the 95th percentile, or in pregnancies with severe FGR (EFW less than the 3rd percentile), we suggest weekly umbilical artery Doppler evaluation (GRADE 2C); (11) we recommend Doppler assessment up to 2 to 3 times per week when umbilical artery absent end-diastolic velocity (AEDV) is detected due to the potential for deterioration and development of reversed end-diastolic velocity (REDV) (GRADE 1C); (12) in the setting of REDV, we recommend hospitalization, administration of antenatal corticosteroids, heightened surveillance with cardiotocography (CTG) at least 1 to 2 times per day, and consideration of delivery depending on the entire clinical picture and results of additional evaluation of fetal well-being (Best Practice); (13) we suggest against the use of Doppler assessment of the ductus venosus, middle cerebral artery, or uterine artery for routine clinical management of early- or late-onset FGR (GRADE 2A); (14) we recommend weekly CTG testing after viability for FGR without A/REDV, and that the frequency be increased when FGR is complicated by A/REDV or other comorbidities or risk factors (Best Practice); (15) we recommend delivery at 37 weeks of gestation in pregnancies with FGR and an umbilical artery Doppler waveform with decreased diastolic flow but without A/REDV or with severe FGR with EFW less than the 3rd percentile (GRADE 1B); (16) we recommend delivery at 33 to 34 weeks of gestation for pregnancies with FGR and AEDV (GRADE 1B); (17) we recommend delivery at 30 to 32 weeks of gestation for pregnancies with FGR and REDV (GRADE 1B); (18) we recommend delivery at 38 to 39 weeks of gestation with FGR when the EFW is between the 3rd and 10th percentile and the umbilical artery Doppler is normal (Best Practice); (19) we recommend that for pregnancies with FGR complicated by A/REDV, cesarean delivery should be considered based on the entire clinical scenario (Best Practice); (20) we recommend antenatal corticosteroids if delivery is anticipated before 33 6/7 weeks of gestation or for pregnancies between 34 0/7 and 36 6/7 weeks of gestation in women without contraindications who are at risk of preterm delivery within 7 days and who have not received a prior course of antenatal corticosteroids (GRADE 1A); (21) we recommend magnesium sulfate for fetal and neonatal neuroprotection for women with pregnancies that are less than 32 weeks of gestation in whom delivery is likely (GRADE 1A).