4.2 Interpretation
In our study, it was demonstrated that the fetal biometric measurements
including EFW, AC, FL and HL of SC-DCDA twins were statistically
different from those of SC-MCDA twins. To date a few number of studies
compared intrauterine growth pattern of DCDA twins to that of MCDA
twins6-8, 11-13, 16, and the results were generally
consistent and similar to the findings of our study. Among which, a
study in Brazil got almost the same result with ours that there were
statistically differences in EFW, BPD, AC and FL between monochorionic
and dichorionic twin pregnancies11. A multicentric
study from Italy also reported that the measurements of EFW, BPD, HC, AC
and FL appeared smaller in MCDA group in comparison with DCDA twins,
however, the difference didn’t show statistical
significance6. When further exploring the
week-specific difference for fetal biometric measurements between DCDA
and MCDA twins, a study conducted in the US found that DCDA twins had
higher sonographic EFW at almost all gestational ages until 34
gestational weeks13, and the data from Italy similarly
found that the differences for AC were statistically significant after
33 week of gestation6. The evidence from the two
studies provided support for our findings.
Fetal growth velocity has been identified as an important indicator to
assess fetal growth and development29. Recently, a
national study in the US examined the growth velocity of six parameters
including EFW, BPD, HC, AC, HL and FL among singletons and compared the
overall differences of these parameters between different
racial/ethnic-specific curves30. To our knowledge, no
study yet paid attention to the fetal growth velocity among twins. ART
has become more common, and an understanding with regard to it’s
perinatal outcome is becoming essential17-20. Several
studies have, more often than not, focused on the possible impact of ART
on birth weight among twin pregnancies, failing to cover intrauterine
fetal growth in the concern17-20. As an initial study,
we, for the first time, observed the gestational week-specific fetal
size and growth velocity among ART-DCDA twins, revealing ART-DCDA twins
had the highest growth rate, followed by SC-DCDA, and then SC-MCDA.