Methods
This was a retrospective cohort study of all MC twins undergoing sIUD at
14-40 weeks from 2012 through 2018 at Shengjing Hospital of China
Medical University. Inclusion criteria included delivery between January
2012 and April 2018 with complete information, including pregnancy
outcomes. The gestational age of birth was assigned based on the first
day of a woman’s last menstrual period. If this dating was not
consistent with dating based on the earliest ultrasound (±7 days in the
first trimester or ±10 days in the second trimester), the gestational
age was reassigned. 9 The gestational age of sIUD was
estimated according to the size of the dead fetus measured via
ultrasound and previous ultrasound. Chorionicity was determined by
ultrasound evaluation according to the presence of the lambda or T signs
and confirmed after birth.10 If the patient did not
undergo chorionic identification ultrasound during pregnancy, the
placenta was examined after delivery to determine the chorionicity.11 sIUD was defined as spontaneous death and
spontaneous death after fetoscopic laser occlusion after 14 weeks of
gestation. Exclusion criteria included sIUD by radio frequency ablation
and miscarriage occurring before 26 weeks and double fetal loss.
Information on each case was recorded to include the following: age
(year), the gestational age of sIUD, parity, the gestational age at
birth, history of fetoscopic laser occlusion, pregnancy
method(including
natural
pregnancy and assisted reproductive conception), fetal complication,
maternal complication, premature rupture of membranes, abnormality in
amniotic fluid, and spontaneous labor or not.
According to the gestational age of birth, the cases were divided into
PTB group (<37 weeks) and full term birth group (>37 weeks). We also
divided these cases into four groups according to the gestational age of
sIUD (14-19weeks, 20-24weeks, 25-30weeks, 31-36weeks) and compared the
four groups using the chi-square test for trends.
Statistical analyses were performed with SPSS software (Version 17.0,
SPSS). Chi-square analysis was performed to test the significance of the
findings. Logistic regression analysis was conducted to determine risk
factors for preterm delivery. P < 0.05 was considered
statistically significant.