New Updates in Fetal Growth Restriction (FGR)

1. Definition and Classification

• FGR vs. SGA distinction sharpened: All current guidelines now clearly distinguish FGR (pathological failure to reach growth potential, usually due to placental insufficiency) from SGA (constitutionally small but otherwise healthy fetus with EFW or AC <10th percentile). A fetus can be SGA without being FGR.
• EFW or AC <10th percentile remains the primary diagnostic threshold, but EFW/AC <3rd percentile (or umbilical artery absent end-diastolic flow, AEDF) is now accepted as definitive FGR even without Doppler confirmation.
• The early/late split at 32 weeks is now universally adopted:
  • Early-onset FGR (<32 weeks): Severe, associated with deep placentation defects, elevated hypoxia markers, high perinatal morbidity.
  • Late-onset FGR (≥32 weeks): Milder placental insufficiency, lower morbidity, but more common and often subtle. Cerebral redistribution (low CPR, low MCA-PI) plays a greater diagnostic role.
• A Delphi consensus on the FGR definition published in late 2025 revisited the 2016 Delphi criteria and addressed implementation challenges after 8 years of real-world use.

2. Screening (First Trimester)

• Combined first-trimester screening (11-14 weeks) is now recommended, incorporating:
  • Uterine artery Pulsatility Index (UtA-PI)
  • Mean arterial pressure (MAP)
  • Serum PlGF (placental growth factor)
  • PAPP-A
• This algorithm identifies high-risk patients for early prophylactic low-dose aspirin.
• The SOGC (2023) and RCOG (2024) guidelines both endorse this FMF-based screening model.

3. Prevention - Low-Dose Aspirin Update

• Aspirin dose raised to 150 mg/day (from 75-100 mg): The DGGG 2024 guideline formally recommends 150 mg ASA starting at ≤16 weeks in women at increased risk of uteroplacental dysfunction.
• Timing: Must be initiated before 16 weeks to have maximum preventive effect on early-onset FGR and preeclampsia.
• LMWH (low molecular weight heparin): Early treatment of placental insufficiency with LMWH is under active investigation (ISUOG 2025 - Figueras). Current evidence is insufficient to recommend routinely, but may be considered in selected high-risk cases (e.g., prior severe FGR, thrombophilia).

4. Diagnosis and Doppler Surveillance

Umbilical Artery (UA) Doppler

Middle Cerebral Artery (MCA) and Cerebroplacental Ratio (CPR)

• New emphasis on CPR in late-onset FGR: In fetuses ≥32 weeks with normal UA Doppler, MCA-PI and CPR are now specifically recommended to guide both surveillance and delivery timing. A low CPR (<5th percentile) reflects cerebral redistribution ("brain sparing") and is an independent risk factor for adverse perinatal outcome.
• CPR should be measured every 2-3 weeks when normal; more frequently if abnormal.

Ductus Venosus (DV) Doppler

• Still reserved for early-onset FGR with deteriorating UA Doppler. Absent or reversed a-wave in DV signals severe venous compromise and imminent fetal acidemia.

Angiogenic Factors (PlGF, sFlt-1)

• A major 2025 RCT in Nature Medicine (Garcia-Manau et al., Nat Med 2025;31:1008-1015) showed that angiogenic factors (PlGF/sFlt-1 ratio) can guide management of late-onset small fetuses comparably to Doppler-based criteria.
• This opens the possibility of angiogenic biomarkers replacing or complementing Doppler in the risk stratification of late-onset FGR, particularly when Doppler findings are equivocal. More data are needed before this becomes routine practice.

5. Investigations in Suspected FGR

• Chromosomal microarray analysis (CMA) is now recommended (not just karyotype) when:
  • FGR is associated with fetal malformation or polyhydramnios (any gestational age)
  • Unexplained isolated FGR is diagnosed <32 weeks
• CMV PCR via amniocentesis should be considered in unexplained FGR (not routine toxoplasma/rubella/herpes screening).
• Routine TORCH screen is no longer recommended in isolated FGR without other risk factors.

6. Timing of Delivery

Early-Onset FGR (<32 weeks)

Late-Onset FGR (≥32 weeks)

• Consensus across RCOG, SOGC, and DGGG that waiting beyond 37 weeks in the presence of any Doppler abnormality is not recommended.
• Induction of labour is acceptable in late-onset FGR; caesarean section is not routinely required unless other obstetric indications exist.

7. Intrapartum and Neonatal Management

• Continuous electronic fetal monitoring (CTG) is mandatory in labour for all FGR cases.
• Antenatal corticosteroids are universally recommended before delivery at <34 weeks. Some guidelines (RCOG 2024) extend this to 35+6 weeks for late preterm FGR.
• Magnesium sulphate for neuroprotection is recommended in early-onset FGR delivered <32 weeks.
• Paediatric/neonatal team should be present at delivery.

8. Postpartum and Recurrence

• Placental pathology examination is recommended after any FGR birth.
• Recurrence risk: 20-30% in subsequent pregnancies after FGR.
• Multidisciplinary preconception counselling is advised before the next pregnancy, including early aspirin prophylaxis planning.
• The SOGC (2023) guideline formally added a section on postpartum management and preconception counselling (PMID 37730302).

9. Emerging Areas (2025-2026)

• AI-powered prediction: ISUOG and others are actively evaluating machine learning models for first-trimester FGR prediction combining biophysical + biochemical markers.
• Extremely early-onset FGR (≤26 weeks): A 2025 systematic review and meta-analysis described the particularly poor perinatal outcomes in this subgroup and the lack of evidence for optimal management.
• Delphi 2025 consensus: 8 years after the original definition, the Gordijn/Ganzevoort group released an updated Delphi consensus addressing gaps in the 2016 criteria and proposing future directions for international harmonization.

• SOGC No. 442 (2023) - Screening, Diagnosis, Management in Singleton Pregnancies
• RCOG Green-top No. 31 (2024) - Investigation and care of SGA/FGR fetus (BJOG 2024;131:e31-e80)
• DGGG/AWMF S2k Guideline (Oct 2024, pub 2025) - German-language guideline with new ASA 150 mg recommendation
• NSW Health GL2025_018 (Oct 2025) - Updated care pathway with 2-weekly serial growth scans
• AJOG International Guideline Comparison 2025 - Consensus and controversies across all major guidelines

New Updates in PIH / Preeclampsia / Eclampsia

1. Classification and Definitions (Refined)

Key Definitional Update (2025 AHA Guideline)

• Chronic hypertension is now redefined as SBP 140-159 or DBP 90-109 mmHg prior to 20 weeks, replacing the older "pre-existing" terminology.
• Preeclampsia no longer requires proteinuria if end-organ dysfunction is present (thrombocytopenia, renal insufficiency, liver impairment, pulmonary oedema, new severe headache, or visual disturbances) - this was introduced by ACOG in 2013 and is now universally adopted across all 2024-2025 guidelines.

2. Prediction and Screening (1st Trimester)

Combined First-Trimester Screening (FMF Algorithm) - Now Mainstream

• Uterine artery Pulsatility Index (UtA-PI)
• Mean Arterial Pressure (MAP)
• Serum PlGF (Placental Growth Factor)
• PAPP-A
• Maternal history factors

Biomarkers for Diagnosis: sFlt-1/PlGF Ratio - Now FDA-Cleared

• Rule OUT preeclampsia with severe features within 1 week (high negative predictive value)
• Rule IN high-risk preeclampsia requiring hospitalization or expedited delivery
• A 2025 meta-analysis (PMID 39947348) confirmed: sFlt-1/PlGF ratio AUC = 0.92, sensitivity 83%, specificity 88% - better than either marker alone.

3. Prevention

Low-Dose Aspirin - Updated Guidance

1. All individuals with chronic hypertension planning pregnancy should be counselled about aspirin for preeclampsia prevention.
2. Low-dose aspirin should be started at 12 weeks gestation in those at moderate-to-high risk.

• Dose: 75-162 mg/day (USPSTF recommends 81 mg; European guidelines favour 150 mg)
• Timing: Must start before 16 weeks for maximum benefit (ideally 11-14 weeks after risk screening)
• Evening dosing is preferred over morning (better absorption and platelet effect)
• Risk: No increased risk of postpartum haemorrhage confirmed in meta-analyses

Calcium Supplementation - New Systematic Review Evidence (2025)

• A 2025 systematic review (PMID 40731825) reaffirmed calcium supplementation (1.5-2 g/day) significantly reduces preeclampsia risk, particularly in low-calcium populations.
• WHO recommends calcium for populations with dietary calcium intake <600 mg/day.
• Some high-income country guidelines (NICE 2023) now recommend calcium in high-risk women regardless of baseline intake.

4. Antihypertensive Treatment Thresholds - Major Update

Biggest Change: Lower the Treatment Threshold

"Pregnant individuals with chronic hypertension should receive antihypertensive therapy to achieve BP <140/90 mmHg"

Current Treatment Targets:

First-Line Antihypertensives in Pregnancy (Unchanged but Reinforced):

• Labetalol (IV for acute; oral for chronic) - first choice
• Nifedipine (oral extended release) - widely used, safe
• Methyldopa - safe but less preferred due to side-effect profile
• Hydralazine (IV for acute) - still used but more side effects than labetalol/nifedipine
• ACE inhibitors, ARBs, direct renin inhibitors - CONTRAINDICATED in all trimesters

5. Management of Preeclampsia with Severe Features

Corticosteroids

• Betamethasone 12 mg IM x 2 doses (24 hrs apart) if delivery expected before 34 weeks.
• NICE (2023) and ACOG both recommend late-preterm steroids (34-36+6 weeks) if delivery anticipated.

Magnesium Sulphate (MgSO4) - Cornerstone, Reinforced

• Indication: ALL cases of preeclampsia with severe features and ALL eclampsia.
• Regime: 4-6 g IV loading dose over 15-20 min, then 1-2 g/hr maintenance.
• Duration: Continue for 24-48 hours postpartum (eclampsia can occur postpartum).
• New data: MgSO4 reduces eclampsia risk by >50% (WHO confirms).
• If eclampsia occurs on MgSO4: re-bolus 2-4 g IV and increase maintenance to 3 g/hr.
• Monitoring: urine output >25 mL/hr, respiratory rate >12/min, patellar reflexes present; antidote is calcium gluconate 1 g IV.

Fluid Management

• Fluid restriction is NOT routinely recommended in stable preeclampsia (updated ANMC 2025 guideline).
• Total IV fluid restriction to 80-125 mL/hr to avoid pulmonary oedema.

6. Eclampsia Management - Updated Protocol

1. Position of safety (left lateral, protect airway)
2. Give MgSO4 STAT (6 g IV bolus if not already on it, then 2 g/hr)
3. If seizure occurs while on MgSO4: re-bolus 2-4 g and increase to 3 g/hr
4. Second-line if seizures persist: diazepam 5-10 mg IV or lorazepam 4 mg IV or levetiracetam (emerging option)
5. Stabilize BP - treat if ≥160/110 with labetalol or hydralazine
6. Delivery should follow stabilization - NOT delayed more than a few hours after seizure control
7. Postpartum monitoring: maintain MgSO4 for 24-48 hrs post-delivery

7. Timing of Delivery

8. HELLP Syndrome Updates

• Definition remains: Hemolysis + Elevated Liver enzymes + Low Platelets
• Platelet threshold for vaginal delivery: >50,000/µL generally safe; <20,000 requires transfusion
• Platelet threshold for regional anaesthesia: >70,000-80,000/µL (updated from older >100,000 threshold in many centres)
• Dexamethasone (10 mg IV Q12h) for severe HELLP to improve platelet count acutely before delivery - used but evidence remains debated.

9. Postpartum Considerations - New Emphasis

• Postpartum hypertension can peak at 3-6 days after delivery - women must be monitored.
• NSAID use postpartum can worsen hypertension - caution advised especially in preeclampsia.
• Long-term CVD risk: Women with preeclampsia have 2x risk of ischaemic heart disease, stroke, and heart failure later in life.
• The 2025 AHA guideline formally classifies a history of HDP as a sex-specific CVD risk enhancer - should be factored into future statin therapy decisions.
• Aspirin should be recommended in subsequent pregnancies starting at 12 weeks.
• Preeclampsia Foundation launched a standardised postpartum wristband initiative (March 2026) to help medical teams quickly identify high-risk postpartum women.

10. Emerging and Future Directions

• Pravastatin: Small studies suggest potential benefit in treating preeclampsia; the 2025 AHA guideline notes larger prospective trials are still needed.
• AI-based prediction models: Combining biochemical + biophysical + AI tools for population-level first-trimester screening is under active development.
• Home blood pressure monitoring: NICE (2023) and Preeclampsia Foundation now actively recommend validated home BP monitors for high-risk patients, enabling early detection of postpartum hypertension.
• Galectins and miRNAs as novel early biomarkers for PE pathogenesis are under investigation (PMID 40012493).

Key Guideline References

• 2025 AHA/ACC Hypertension Guideline - Section 5.5 (Hypertension and Pregnancy) - multiple new Class I recommendations
• ACOG Practice Bulletin 222 (updated 2024) - Biomarker Prediction of Preeclampsia With Severe Features
• NICE Guideline NG133 (updated 2023) - Hypertension in Pregnancy
• French CNGOF Guidelines (2024) - PMID 37891152
• ISSHP Classification (2021, still current) - International Society for the Study of Hypertension in Pregnancy
• sFlt-1/PlGF meta-analysis 2025 - PMID 39947348
• Creasy & Resnik's Maternal-Fetal Medicine (9th ed.) - Chapter 45, foundational pathophysiology