Understanding Early Onset Foetal Growth Restriction

MedPiper Technologies and JournoMed had conducted a World Preeclampsia Week Webinar Series in association with National IRIA Preventive Radiology and Samrakshan Committees where the speakers discussed Early-onset foetal growth restriction on 27th May, 2022.

Prof. Dr Shibani Mehra, President of IRIA, New Delhi stressed on preventive radiology and the role of radiologists in preventing eclampsia, early FGR etc. An awareness must be created among the radiologists and the pregnant women regarding pre-eclampsia and foetal maternal environment. IRIA’s Samrakshan Program has helped to reduce maternal and foetal mortality rates in India. Since pregnancy complications are unpredictable, they can negatively impact antenatal and foetal outcomes. Foetal growth must be monitored carefully and any foetus with IUGR (intrauterine growth restriction) needs special care through the pregnancy period.

One of the speakers was Dr Kavita Aneja who is a radiologist, sonologist and foetal medicine specialist. She mainly spoke about early-onset foetal growth restriction (caused by pre-eclampsia) which is a major contributing factors for increased perinatal mortality in India and Worldwide. Research shows that early foetal growth restriction can be diagnosed using foetal doppler imaging, thus resulting in better outcomes. Doppler imaging also recommended by the Samrakshan Program.

Samrakshan Protocol – Screening for pre-eclampsia and foetal growth restriction 

With the help of Samrakshan, radiologists working both in India and globally grasp the significance of preventive radiology. They monitor results using doppler or ultrasound scan to diagnose antenatal complications and growth retardations on time and formulate appropriate interventions. 

Samrakshan is a national program of IRIA that addresses the high rates of perinatal mortality, low birth weight and preterm babies in India. The project was initiated by Dr Rijo Mathew and it aims to reduce perinatal mortality in India.

5 Steps approach in First-trimester screening

Step 1: Noting down the maternal history

Step 2: Measuring mean arterial blood pressure (MAP)

Step 3: Uterine artery doppler PI at 11-14 weeks

Step 4: Calculating the patient-specific risk for pre-eclampsia and foetal growth restriction

Step 5: Filling up of online Samrakshan forms

Foetal growth restriction, an important issue

Data shows that 26-30% of pregnancies in India have small foetuses i.e. every 3rd pregnant mother carries a small foetus. These foetuses are at a 4-8 times higher risk of perinatal mortality when compared to their appropriate-sized counterparts as they are susceptible to foetal growth restrictions. After birth, these babies may experience abnormal neurologic development and gastrointestinal problems.

How to identify small foetuses? 

Step 1: Establish the gestational age 

Step 2: Estimate the foetal weight

Step 3: Calculate the weight percentile 

How to determine the gestational age?

Last menstrual period

The last menstrual period values must be known correctly so as to obtain the dating scan and estimated due date values.

Dating Scan:

Dating scan helps to predict the estimated due date (EDD) of pregnancy. A percentile or a centile is a measure used in statistics indicating the value below which a given percentile of observations in a group of observations fails. Centile value are gestational age-dependent. (The centile values and the PI values differ for different vessels such as umbilical artery, foetal middle cerebral artery, mean uterine artery, ductus venosus etc.) The centile values might be incorrect if the dating scan values are not properly calculated which in turn affects the redating centile values. Hence, it is important to accurately calculate centile and gestational age values.

If the variation between the ultrasound dating and the last menstrual period dating is more than what is expected, redating the pregnancy is necessary. 

Assigned delivery date 

• The mother must be aware of the EDD and should go for redating if they are not aware of it.
• Once assigned, never change the EDD in the subsequent reports
• A pregnant woman must carry the previous scans reports (the importance of carrying report scans should be emphasized)

Estimating the foetal weight

The foetal weight is estimated by optimal weight prediction formulae and by sonographic measurement

Small for gestational age foetus/ Small foetus: The small for the gestational age foetus is a small foetus whose foetal weight is less than 10th centile for gestational age. The gestational age is assigned to the mother during the dating scan and assigning the accurate age is extremely crucial. 70% of the foetuses of small gestational age may have a risk of perinatal mortality. 

FGR or Foetal growth restriction 

FGR is a functional problem of unmet foetal need- pathology in the placenta not able to meet the increased demand. The foetus is unable to reach the genetic potential because of unfavourable environmental conditions i.e. nutrition and oxygenation from the placenta. 

Early-onset FGR: In the early-onset foetal growth restriction, the gestational age commences before 32 weeks of pregnancy. Greater than 30% of the placenta is damaged due to this early-onset FGR.

Late-onset FGR: The late-onset FGR, the gestational age commences after 32 weeks of pregnancy.

Role and Importance of Placenta in FGR

The Placenta is a unique two-compartmental organ which aids the maternal foetal exchange.

• Maternal compartment- supplied by uterine artery (which tells about placenta)
• Foetal compartment- supplied by umbilical artery (tells about placental compromise)

Effect of placental dysfunction

The two factors responsible for foetal growth are nutrition and oxygenation. Placental dysfunction can cause foetal smallness due to intrauterine malnutrition, and foetal compromise from respiratory hypoxemia. 

Cardiovascular adaptation: The umbilical artery has high resistance as it supplies the blood to the foetus. In the case of the diseased placenta, the umbilical artery fails to supply blood which eventually results in foetal cardiac arrest.

Brain Stem Suppression: The immature brain stem is resistant to hypoxia and results in doppler abnormalities during early-onset FGR. The doppler triggers when the brain stem is suppressed, which results in cardiac arrest.

Tools to gauge FGR

Growth velocity curves and doppler signs are used in the prognosis and diagnosis of FGR. These values reflect placental disease, foetal growth restrictions and foetal adaptation conditions which causes hypoxia. 

Managing FGR – The challenge

Managing foetal growth restriction is the greatest challenge where the balance between the intrauterine hypoxic result vs premature delivery should be observed. Extra uterine risks in the neonatal intensive care units (NICU) should also be determined.

The stage-based management protocol was studied based on the best available evidence. The Barcelona Protocol by Eduard Gratacos and Team is commonly preferred for early and late-onset FGR. It’s a simple algorithmic approach that is easy to follow.

Conclusion

If pre-eclampsia and FGR screening is performed, there would be a significant reduction in the perinatal and maternal mortality rates. Pregnancy is a physiological phenomenon where the mother must be patient and if they suffer from pre-eclampsia, they can be cured using the advanced options of preventive radiology.