| Part Ⅰ:The Influence of the Vanishing Twin on the Perinatal Outcome of Surviving Singleton in IVF PregnancyBackground:Vanishing twin syndrome(VTS)refers to the pregnancy loss of one of the fetuses in twin pregnancy.The incidence of VTS in in vitro fertilization(IVF)or intracytoplasmic sperm injection(ICSI)pregnancy is about 5-30%.Different from the original singleton,the surviving singleton with vanishing twins is more or less exposed to the intrauterine environment of twin pregnancy,which may be a risk factor for adverse pregnancy outcomes such as low birth weight,increased incidence of preterm birth and even stillbirth.Objective:The purpose of this study was to clarify the influence of the vanishing twin(VT)on the perinatal outcomes in the surviving singleton,and further identify the susceptible window.Methods:This study followed a retrospective cohort design and retrospectively recruited parturients who obtained single live births through in vitro fertilization and embryo transfer(IVF-ET)in our hospital from July 2014 to December 2017.Through ultrasound monitoring at 6-8 weeks of gestation and 11-13 weeks of gestation,those who had two gestational cysts but were born in the form of singleton were divided into exposure group and those who had only one gestational sac and were born in the form of singleton were divided into original singleton group.In order to further determine the impact of the occurrence time of vanishing twins on the perinatal outcome of offspring,those whose occurrence time of vanishing twins is earlier than or equal to 13 weeks of gestation are divided into early vanishing twins(EVT)and those whose occurrence time of vanishing twins is greater than 13 weeks of gestation are divided into late vanishing twins(LVT).Excluding the use of egg donor,sperm donor,ultrasound monitoring records in the first three months of missing pregnancy and monozygotic twins.In this study,a total of 11784 singletons were included,including 636 surviving singleton with vanishing twins(593 EVT and 43 LVT)and 11148 original singletons.The baseline information,perinatal complications and perinatal outcomes of the recruited subjects were sorted out and statistically analyzed.Results:In our birth cohort,about 5.4%of all singleton deliveries were originated from vanishing twin pregnancies.Compared with the singletons,both EVT and LVT had a significantly lower birth weight(3337.57±532.24g vs 3446.15±526.07g,P<0.001;2916.05±526.07g vs 3446.15±526.07g,P<0.001),more frequent neonatal jaundice(47.0%vs 40.6%,P=0.002;60.5%vs 40.6%,P=0.008),and decreased incidence of umbilical cord abnormality(15.5%vs 19.9%,P=0.009;7.0%vs 19.9%,P=0.034).Newborns in early VT group were more likely to manifested as SGA(5.4%vs 3.6%,P=0.002)and suffered oligohydramnios(5.4%vs 3.4%;P=0.009)than the original singletons.In addition,the gestational age of LVT group were shorter than the original singletons(37.25±3.25 vs 39.04±1.63,P=0.001),and had a significantly higher risk of PTB(30.2%vs 6.6%;P<0.001)and NICU admission(27.9%vs 9.4%,P<0.001).All differences except for SGA maintain significant after adjusted for maternal age,BMI and parity.Conclusions:Singletons with a vanished co-twin had worse perinatal outcomes compared with the original singletons.LVT burden even much on the survival one.Therefore,close monitoring during perinatal period was suggested in this type of neonates.And elective single embryo transfer should be also fully considered which could tackle the problem at its root.Part Ⅱ The Influence of the Vanishing Twin on the Long-term Health of Surviving Singleton in IVF PregnancyObjective:To further explore the impact of vanishing twins on the long-term growth and development of surviving singleton,in order to have a comprehensive understanding of the long-term health outcomes of vanishing twins,provide guidance for the health management of this population,and put forward suggestions for the formulation and management of strategies related to assisted reproduction.Methods:We performed a historical and prospective cohort study,this study analyzed the offspring o who received IVF in the affiliated reproductive Hospital of Shandong University from July 2014 to December 2017.They were divided into control group and vanishing twin group according to the occurrence of vanishing twin syndrome monitored by early pregnancy ultrasound.Stratified according to the follow-up age of offspring:≤ 1 year old is the infant group,>1 and ≤3 years old is the toddler group,>3 and ≤7 years old is the preschool group,and>7 years old is the school-age group.The physical development indexes,including height,weight and body mass index(BMI),were compared between the vanishing twins group and the original singleton group;Ages and Stages Questionnaire was used to evaluate the mental and motor behavior of offspring,including five units:communication ability,gross movement,fine movement,problem-solving ability and social ability;Wechsler Intelligence Scale was used to compare the intelligence level of offspring in vanishing twins group and original singleton group.Results:In the infant group,there was no difference in physical development indicators between the singleton group and the vanishing twin group.The proportion of weight Standard deviation scores(SDS)greater than 2 in the disappearing twin group(15.4%)was significantly lower than that in the singleton group(25.2%),and the results were statistically different(P=0.022);in the toddler group,the height-SDS in the vanishing twin group was significantly lower than the singleton group(0.35±0.89 vs 0.52±1.05,P=0.015),and the weight-SDS ratio of the vanishing twin group(6.3%)was significantly lower than that of the singleton group(11.3%).In the communication unit,the score of the vanishing twin group was higher than that of the singleton group(58.75±4.73 vs 57.73±6.55,P=0.047);in the preschool group,there was no difference in the physique development indexes between the singletons and the vanishing twins.In the gross movement unit,the score of the vanishing twin group was higher than that of the singleton group(59.87±0.81 vs 59.55±2.35,P=0.014).In the score of language comprehension index and total IQ score,the vanishing twin group had lower scores than the singleton group(99.43±25.43 vs 112.45±13.92,P=0.025;105.35±14.47 vs 112.87±10.77,P=0.026);There was no significant difference in the physical development index,offspring behavior and intelligence level between the singleton group and the vanishing twin group.Conclusion:Vanishing twin syndrome affects the physical development of infants and toddlers,and has a certain impact on the behavior and intellectual development of preschool-age offspring,but these differences may be compensated for by acquired development,which was not observed in school-age offspring difference. |
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