FETAL GROWTHDr. Agus Rusdhy Hariawan Hamid, SpOG

Traditionally obstetricians have expended most effort on the identification of the small-fordates fetus.

The reason for this effort is that a significant number of small babies have suffered from Intra-Uterine Growth Restriction (IUGR).

The small-for-dates fetus may be so constitutionally.

It is logical to state also that some fetuses may have failed to reach their genetic growth potential but still be heavier than the tenth centile for weight.

This aim is nevertheless justified by the higher perinatal mortality rate in these small babies.

IUGR may be associated with some maternal complications in pregnancy or the result of toxic insult or fetal abnormality.

Attention should be directed to those in certain groups:

Clinically suspected poor growth. Hypertension in pregnancy (regardless of cause). Maternal medical disorder e.g. renal disease Antepartum haemorrhage. Diabetes (with microvascular disease). Multiple pregnancy. Previous IUGR. Previous bad obstetric outcome. Toxins, particularly tobacco, alcohol, illicit drug

use.

The only reliable assessment of fetal growth is based on ultrasound measurements of the fetus.

Serial measurements of the fetal biparietal diameter, abdominal circumference, head circumference and long bones can be measured.

In cases of IUGR there is the phenomenon of head sparing in which blood flow to the head is maintained in preference to other organs.

This results in an increase in the ratio of the circumference of the head to that of the abdomen.

This increase in the head/abdomen circumference ratio is said to identify 'assymetric' growth restriction.

The small fetus in which the head/abdomen circumference is normal is said to exhibit 'symmetric' growth restriction.

It is likely that some of these babies are constitutionally small rather than being truly growth restricted.

Although diverse interventions have been attempted in order to improve the outcome or mitigate the insult that leads to IUGR, most interventions have generally had little impact on the clinical outcome or its sequelae.

It is clear that attempts should be made to remove the cause of feto-placental injury, such as improved nutrition, smoking cessation, treatment of infectious diseases, avoidance of illicit drugs and control of maternal disorders including hypertension and renal dysfunction.

It is also imperative to exclude any lethal fetal malformations that could make any further management irrelevant.

Therefore, ultrasonographic evaluation for such malformations and options of fetal karyotyping must be considered.

Currently, there is no single test that indicates the optimal timing of delivery.

Considerations for delaying the delivery as much as feasible in order allow the fetus to gain maturity are counter-balanced not only by the need to deliver prior to fetal death, but also prior to any permanent injury to the brain or other vital fetal organs.

After 34 completed weeks the appearance of advanced, worsening signs of fetal deterioration, such as absent or reversed UA diastolic flow, persistent nonreassuring NST, a BPP score of 4, reversed ‘a’ wave of the ductus venosus or umbilical vein pulsations may suggest the need for immediate delivery.