3.2 Modeling fetal growth reference
As shown in Table S3, S4 and S5 , both the overall growth curve
through 14 to 37 weeks of gestation and each fetal biometric measurement
according to gestational age were compared among the three groups. The
statistical differences occurred in the fetal biometric measurement
curves for EFW, AC, FL and HL between SC-DCDA and SC-MCDA
twins, and the size of each
biometric measurement appeared to be smaller in SC-MCDA (allp <0.05). The growth velocity for EFW, BPD, HC, FL and
HL of SC-DCDA twins was also different from those of SC-MCDA twins (allp <0.05), but no statistical differences were found in
AC. When evaluating week-specific differences in the biometric variables
between SC-MCDA and SC-DCDA twins, the results presented that EFW, FL
and HL growth slowed down in SC-MCDA twins compared with SC-DCDA during
most of the gestational weeks (p <0.05). In addition,
the size of all the six fetal biometric measurements demonstrated
smaller through 15, 21 and 25 weeks of gestation in SC-MCDA twins than
that in SC-DCDA twins consistently (p <0.05). When the
comparison between SC-DCDA and ART-DCDA groups was examined, significant
differences were observed in all
of the six fetal biometric measurements curves and only in the growth
velocity for HC (all p <0.05). Similarly, week-specific
differences of all the six fetal biometric measurements were significant
at a few weeks of gestation (all p <0.05). Further
focusing on SC-MCDA and ART-DCDA twins, it was found that there were
significant differences in all of the six fetal biometric measurements
curves and the growth velocity of EFW, BPD, HC, FL and HL. Meanwhile,
week-specific differences of all the six fetal biometric measurements
were statistically significant during most gestational weeks.
Tables S6, S7 and S8 showed that all of the SC-MCDA, SC-DCDA
and ART-DCDA twins were different from singletons, especially during the
third trimester.
Figure 2, 3 and 4 show the fitted growth curves of fetal
biometric parameters, including EFW, BPD, HC, AC, FL and HL for SC-MCDA,
SC-DCDA and ART-DCDA twins, respectively. The smoothed percentiles, such
as the 5th, 10th, 50th, 90th, and 95th percentiles of fetal biometric
parameters by gestational age are illustrated in Table S9 .