GENDER DIFFERENCES IN FETAL CEREBRAL BLOOD FLOW

1
GENDER DIFFERENCES IN FETAL CEREBRAL BLOOD FLOW

• Seong Jin Choi, M.D., In-Bai Chung, M.D., Dong
  Soo Cha, M.D.
• Department of Obstetrics and Gynecology, Yonsei
  University, Wonju College of Medicine, Wonju,
  Korea

Objective There is general consensus that male
gender is associated with higher neonatal
mortality and neurodevelopmental morbidity in
preterm neonates. However no specific mechanisms
for the increased risks have been identified. In
this study, we report our findings regarding the
gender differences in fetal cerebral blood
flow. Methods Doppler ultrasonographic
examination was performed to measure fetal middle
cerebral artery (MCA) and anterior cerebral
artery (ACA) pulsatility index (PI) in 71 normal
pregnancies between 25 and 39 weeks gestation.
Gender determinaion was possible in 44 fetuses by
postnatal examination or genetic amniocentesis.
The gestational weeks were grouped into 4-week
sections. Group I ranged from 28 to 31
gestational weeks. Group II and III ranged from
32 to 35 and from 36 to 39 weeks, respectively.
Results The ACA PI of the male fetuses decreased
with increasing gestational time (group I 1.7917
? 0.3497, group II 1.5710 ? 0.6672, group III
1.3053 ? 0.3450 P lt 0.05). The ACA PI of the
female fetuses also decreased significantly
(group I 1.9714 ? 0.5869, group II 1.6846 ?
0.4123, group III 1.3338 ? 0.2088 P lt 0.05).
The MCA PI of the male fetuses decreased (group
I 2.0204 ? 0.5821, group II 1.8822 ? 0.4282,
group III 1.5347 ? 0.4668 P lt 0.05). However,
there was no significant decrease in the MCA PI
of female fetuses (group I 2.1397 ? 0.5966,
group II 1.8705 ? 0.5607, group III 1.8810 ?
0.4016 P 0.827). Conclusion These data
demonstrate that female fetuses show a relatively
constant middle cerebral artery PI regardless of
the gestational time. It can be one of the
possible cause of better perinatal outcome in
female preterm neonates.
INTRODUCTION

• Doppler sampling
• Angle of insonation was always less than 30º
• Sample volume was placed
• 1 cm from the beginning of each vessel
• as it originates from the circle of Willis
• Analysis of data
• PI V1 V0 / Vmean
• V0 end diastolic velocity
• V1 peak systolic velocity

• The normal range of the ACA and MCA PI was
  established thoughout pregnancy. ( Figure 2.,
  Table 2.)

• A Doppler study of the fetal arteries
• useful tools for evaluating the fetal well-being
• General consensus
• Male preterm neonates are associated with higher
• mortality
• neurodevelopmental morbidity
• than female preterm neonates
• Post natal study (Baenziger et al) Pediatr
  Neurol 199411319-324
• Cerebral blood flow preterm boys gt preterm girls
  
• We observed gender differences in fetal cerebral
  artery blood flow.

Table 2. Normal range of the fetal ACA and MCA PI
(95 confidence interval)
RESULTS

• Grouped into 4-week sections
• Group I 28 31 gestational weeks
• Group II 32 35 gestational weeks
• Group III 36 39 gestational weeks
• No significant variation in the age and parity
• ( Table 1.)

METHODS

• Study population
• Inclusion 71 uncomplicated pregnant women
• During study period 4 women were excluded
• Due to gestational DM or fetal growth restriction
• Gender determinaion was possible in 44 fetuses by
• postnatal examination or
• genetic amniocentesis
• We measured fetal cerebral artery PI every 4
  weeks.
• Identification of fetal cerebral artery
• Color Doppler imaging in an axial view of the
  fetal head at the level of the cerebral
  peduncles
• ACA running perpendicular to a transverse line
  passing anterior to the cerebral peduncle
• MCA running anterolateral to the cerebral
  peduncle, close to the greater wings of the
  sphenoid

• We analyzed the ACA and MCA PI data by
  gestational age and fetal gender. (Table 3.)

Table 3. ACA and MCA PI grouped by gestational
weeks group and gender
Table 1. Age and parity
CONCLUSION

• male and female ACA PI decreases with
• male MCA PI increasing gestational
  time
• female MCA PI relatively constant
• It can be one of the possible cause of better
  perinatal outcome in female preterm neonates.

Abbreviation ACA anterior cerebral
artery MCA middle cerebral artery PI pulsatility
index
Figure 1. Power Doppler images and velocimetries
in the ACA (left) and MCA (right).
Figure 2. PI from the fetal ACA (left) and MCA
(right) for normal pregnancy relative to
gestational age.