When uterine height is measured at each visit starting from week 26 of pregnancy, an ultrasound EFW is required if the value obtained is less than the 10th percentile for gestational age and there is no EFW in the previous 2 weeks. It is measured in three steps to make an estimate of fetal weight. These steps are as follows;
• 1st step: Pregnancy dating is made according to the length of the head-butt,
• Step 2: Calculation of EFW based on fetal biometry is Hadlock’s algorithm that includes biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). If cephalic measurements are not valuable, an alternative algorithm is used with FL and AC,
• 3rd step: The growth percentage is calculated according to reference tables,
However, some factors should be taken into consideration for detailed anamnesis and these are as follows:
• Toxic habits: tobacco, alcohol, drugs, drugs and work
Measuring mother and father weight, size, patient’s weight at birth and blood pressure (BP) at the beginning of pregnancy
Sexual history of the couple, duration of intercourse, type of contraception and artificial insemination techniques,
Previous obstetric clinical history, neonatal weight of previous children (previous small for gestational age (SGA) history doubles the risk in consecutive pregnancies), history of fetal death, preeclampsia, growth restriction, recurrent miscarriages, placental abruption and premature births,
Medical history, diabetes with vascular disease, moderate and severe nephropathy, cyanotic congenital heart disease, arterial hypertension, antiphospholipid syndrome and systemic lupus erythematosus,
• Maternal physical examination, weight, height, uterine height, limb examination in search of chronic vascular disease, blood pressure.
Complementary Tests to Diagnose Fetal Growth Retardation
For the diagnosis and diagnosis of fetal growth retardation, some complementary tests other than the medical histories of the mother or father are applied. These tests are as follows:
A detailed anatomical evaluation is made with ultrasound. 20-60% of congenital malformations are accompanied by growth disturbance, and approximately 10% of growth-restricted fetuses have a congenital anomaly associated with it. It is also important to evaluate the Doppler study (UA, middle cerebral artery (MCA) MCA, UtA, and CPR), placenta, amniotic fluid, and chromosomopathy markers.
Neurosonography and echocardiography
Proteinuria study and a whole blood test (with liver and kidney profile) with hemogram, coagulation and basal biochemistry is performed for growth below the 3rd percentile.
When IUGR is diagnosed at early gestational ages, an amniocentesis is recommended to exclude chromosomal abnormalities. The rate of chromosomal abnormality in fetuses with growth retardation is approximately 20% if diagnosed before 23 weeks. Genetic studies in amniotic fluid are recommended when any of the specified criteria are encountered. These criteria are as follows:
Quantitative fluorescence-polymerase chain reaction (QF-PCR) and molecular karyotype (sequence CGH),
Diagnosis of IUGR before 24 weeks and when severe
Ultrasound markers (except oligoamnios) before 28 weeks and severe with minor structural anomaly or biometry (femur length (FL) or HC),
When EFW is lower than the 10th percentile accompanied by any major structural anomaly,
• To examine bone changes,
If bone biometry is 3 SD or femur / foot ratio is <0.85, then achondroplasia and hypochondroplasia
If there are dysplasia, bone morphological changes or malformations associated with long bone length below the 1st percentile,
• For specific genetic panels or exome sequencing study
• When two systems with high risk of syndrome (except hypospadias) have growth retardation with more than one structural anomaly,
Infection is estimated to have an infectious cause in about 5% of small-for-gestational age (SGA) fetuses. The most common pathogen is CMV, followed by toxoplasma and syphilis. When faced with a diagnosis of IUGR), some tests are requested and these are as follows:
• Rubella test,
Syphilis, treponemal and reaginic test in maternal blood,
• Malaria test, for populations at risk (from endemic areas),
• CMV test, if the invasive technique is indicated, CMV PCR in amniotic fluid is required. If the invasive technique is not specified, maternal serologies (IgG and IgM) are requested only in IUGR except small for gestational age (SGA). If IgG and IgM are negative, the infection is discarded, and if positive, amniocentesis for CMV PCR in amniotic fluid is recommended. If IgG is positive but IgM is negative, it is recommended that amniocentesis be performed only if there is an ultrasound marker compatible with CMV infection (except an isolated oligoamnios).
Following Fetal Growth Retardation
Follow-up visits for the Doppler study are adapted according to the degree of fetal involvement and these are as follows:
• Small for gestational age (SGA): Checked every 2-3 weeks,
• IUGR stage I: checked every 1-2 weeks,
• IUGR stage II: Checked every 2-4 days,
• IUGR stage III: It is checked every 24-48 hours,
• IUGR stage IV: Checked every 12-48 hours
Doppler control and CTG are performed during visits, while EFW assessment is done at intervals equal to or longer than 15 days. When severe preeclampsia accompanies IUGR, follow-up should immediately correspond to the phase of upper growth retardation.
Gestational Age and Birth for Fetal Growth Retardation
The moment of optimal termination requires a balance between the risks of premature and intrauterine persistence (death due to inadequate tissue perfusion and multi-organ damage). The purpose of IUGR wakefulness is to evaluate fetal and neonatal risks and choose the best delivery route to optimize intervention times.
Depending on the gestational age at which terminated, there are various degrees of premature probability and these are as follows:
• In the extremely premature (24–28 weeks) period, each additional day of pregnancy represents a 1-2% increase in survival chance. It is considered to be less than 26 weeks in the baby whose environment is less than 50% chance of survival without serious sequelae,
In the moderately premature (28-34 weeks) period, the presence of reverse flow in the umbilical artery is associated with an RR of 10.6 for the development of perinatal morbi-mortality.
• In the late premature (34-36 weeks) period, there is neither a high mortality rate nor severe morbidity, but a worse perinatal and cognitive outcome. The decrease in diastolic velocities of the umbilical artery is associated with fetal malnutrition and neurodevelopment. The fetus without telediastolic flow of the umbilical artery is at a four-fold higher risk in terms of serious morbidity and perinatal mortality.
During full pregnancy (> 37 weeks), cerebral hemodynamic redistribution is associated with worse perinatal and cognitive outcomes.
Delivery in growth restricted fetuses is associated with an increase in the rate of emergency cesarean delivery. Therefore, elective cesarean is recommended in the presence of severe fetal deterioration signs such as the absence or reversal of umbilical diastolic flow. However, cervical ripening begins with a PGE2 slow release device, mechanical methods or oxytocic induction, depending on cervical conditions and uterine dynamics. Since intrapartum obstetric behavior is in question, continuous monitoring is required. It is also important to perform a placental anatomo-pathological study that is appropriate for the baby’s weight and in any case.
Finally, it is very important to improve the diagnosis of fetal growth restrictions and fetuses. Therefore, first trimester ultrasound is required for accurate dating of pregnancy. A second trimester ultrasound should be performed to detect fetal anomalies, to detect the most severe and early fetal growth restriction (FGC) cases, and a third trimester ultrasound to increase the diagnosis of late fFGC. In addition, additional ultrasounds are recommended during the third trimester in cases with risk factors for growth defects. A careful etiological diagnosis should be made to exclude malformations, infections or genetic changes. The management and follow-up of these pregnancies should be based on clinical evidence-based systematic protocols that facilitate incorporation of clinical practice.
Writer: Ozlem Guvenc Agaoglu