This thesis of Hester Kamphof contributes to the knowledge about diagnosis and management of fetal growth restriction (FGR), which is when a fetus is too small. The smaller the fetus, the higher the risk of FGR. However, small fetuses may have achieved their growth potential and be healthy while fetuses within the “normal size range” might have not met their growth potential. The 10th percentile (p10) is usually used as cut-off for “too small”. In absolute numbers, most complications however occur in fetuses >p10. Factors such as inaccuracy of ultrasound measurements further complicate FGR detection.
We found that in low-risk populations the predictive value for perinatal complications of slow fetal growth is low. Constructing sex-specific growth-curves only slightly improves the detection of FGR.
The DRIGITAT study had a high-risk population with an estimated fetal size <p10. The goal was to evaluate the effect of immediate delivery from 34 weeks of gestation onwards in case of abnormal resistance profiles in the blood vessels of the placental circulation and fetal brain. There was no evidence that this intervention prevented complications. If the resistance profiles were normal, significantly fever complications occurred. We found that the maternal BMI, gestational age and fetal size at inclusion, the resistance profiles, fetal growth velocity, preeclampsia and sFLT/PLGF ratio were associated with complications. We combined these variables into a prediction model with an area under the curve (AUC) of 0.77.
When making a risk assessment in case of suspected FGR, it is important to evaluate all available diagnostic measures instead of only fetal size as “normal” fetal size does not rule out FGR. Future research should therefore also focus on this group.
