Comparing pregnancy outcomes in a population with natural versus surgical reduction of twin pregnancies: a retrospective cohort study

Objective To compare the cycle of initial twin pregnancy with vanishing twin syndrome (VTS), the cycle of initial twin pregnancy after surgical reduction, and the live birth outcome of initial singleton pregnancy. To provide clinical evidence for confirming that vanishing twin syndrome (VTS) and surgical reduction may affect obstetric and perinatal outcomes. Methods A retrospective study was conducted on patients diagnosed with MFPR and VTS at the Reproductive Medicine Hospital of the First Hospital of Lanzhou University from January 2017 to December 2021. A total of 1,796 singleton patients were ultimately included, comprising 271 patients with naturally reduced twin pregnancies, 84 patients with surgically reduced twin pregnancies, and 1,441 patients with singleton pregnancies after IVF/ICSI-assisted conception. A comparison was made on the clinical characteristics and pregnancy outcomes of the three groups. Results The rates of preterm birth and low birth weight in the MFPR group were significantly higher than those in the VTS group and the control group (P < 0.05). The miscarriage rate in the MFPR group was significantly higher than that in the VTS group (P < 0.05), but there was no statistically significant difference compared with the control group (P > 0.05). In contrast, the VTS group showed comparable gestational age and birth weight to the control group, with an even lower miscarriage rate. Within the MFPR cohort, Monochorionic diamniotic twin pregnancy (MDT) pregnancies had a higher risk of miscarriage than Dichorionic diamniotic twin pregnancy (DDT) pregnancies (P<0.05). ROC analysis indicated that serum β-hCG levels on day 14 post-transfer had value in distinguishing VTS from initial singletons (AUC = 0.75), with a cutoff of 837 mIU/ml. Conclusions The VTS population may have better pregnancy outcomes than the MFPR population and the β-hCG level has certain clinical application value. At the same time, the MFPR in DDT pregnancy is more challenging than that in MDT pregnancy.