Subclassification of small-for-gestational-age fetus using fetal Doppler velocimetry. 
Our purpose was to determine whether small-for-gestational-age (SGA) fetus can be divided to subclassified groups using fetal Doppler velocimetry.  Fifty-four pregnant women with SGA infant delivered after 37 weeks of gestation were studied.  After 24 weeks of gestation, fetal middle cerebral artery puslatility index (MCAPI) and umbilical artery pulsatility index (UAPI) were measured at 2- to 3-week intervals using Doppler ultrasound.  Perinatal outcomes [operative delivery due to fetal distress, abnormal fetal heart rate (FHR) pattern, meconium staining, low Apgar score (<7), neonatal acidosis (umbilical artery blood pH <7.15), neonatal intensive care unit (NICU) admission due to neonatal asphyxia, and decreased amniotic fluid] were compared in subclassified SGA groups using fetal Doppler velocimetry.  The number of SGA fetuses with normal MCAPI and UAPI (normal SGA group) was 39, and those with significantly low MCAPI but normal UAPI (eventful SGA group) 15, respectively.  Birth age and birth weights in the eventful SGA group were significantly earlier and lower than those in the normal SGA group, respectively (p < 0.05, and p < 0.005).  There were significant increases in operative deliveries, abnormal FHR patterns and decreased amniotic fluid in eventful SGA group, when compared with events related to normal SGA group.  However, there were no significant differences in meconium staining of amniotic fluid, low Apgar score, neonatal acidosis, and NICU admission between the two groups.  These results suggest that SGA fetus with abnormally low MCAPI but normal UAPI has more poor perinatal outcomes, compared with that with normal MCAPI and UAPI.