- Staging of fetal growth restriction and optimal timing of delivery.

 

Staging of fetal growth restriction and optimal timing of delivery

 

The optimal timing of delivery with FGR is determined by the severity of

fetal compromise and the risk of stillbirth:

1.     Stage I (mild placental insufficiency): Abnormal Doppler studies including CPR ratios.

2.     Stage II (severe uteroplacental insufficiency): There is absent EDV in the UA. Delivery should be after 34 weeks with twice-a-week monitoring.

3.     Stage III (fetal deterioration, low suspicion of fetal acidosis): There is a reversal of EDV in the UA or DV PI >95th percentile. Risks of stillbirth and neurologic handicap are increased. Delivery should be around 32 weeks.

4.     Stage IV (fetal acidosis): Spontaneous fetal decelerations, reduced variability or reversal of atrial flow on DV. Imminent risk of fetal demise. Deliver immediately.

 

Also timing of delivery should be individualized and based on gestational age and fetal condition. The following principles may guide management of pregnancies complicated by IUGR:

·       Remote from term, conservative management to prolong pregnancy may be performed safely with serial antepartum surveillance as described earlier to achieve further fetal maturity.

·       The term or late preterm (>34 weeks) IUGR fetus should be delivered when there is evidence of maternal hypertension, poor interval growth (over 2- to 4-week intervals), nonreassuring antenatal testing (NST, BPP), and/or umbilical artery Doppler testing to demonstrate absence or reversal of flow.

·       When growth restriction is mild, no complicating maternal or fetal factors are present, and the umbilical artery Doppler and fetal testing are reassuring, delivery can be delayed until at least 37 weeks to minimize the risks of prematurity.

·       Each specific clinical scenario requires close consideration and an individualization of management plans.

Alternatively, delaying delivery until the fetal heart rate pattern is abnormal has been reported to result in a nearly fivefold increase in stillbirths, therefore, if a fetus with growth restriction has an abnormal umbilical artery waveform, twice daily monitoring of the fetal heart rate pattern is recommended, and delivery should be undertaken as soon as the heart rate pattern becomes abnormal.