Analysis of related factors of monozygotic twins in assisted reproductive techniques and the clinical outcomes of dichorionic triplet pregnancy which reduced one monochorionic twin

Abstract

Objective To investigate the incidence of monozygotic twins (MZT) and the clinical outcomes of dichorionic triplet pregnancy which reduced one monochorionic twin after multifetal pregnancy reduction with assisted reproductive techniques (ART). Methods A retrospective analysis was performed in 196 patients who underwent vaginal multifetal pregnancy reduction after ART. The proportion of MZT in different groups was analyzed, and the clinical outcomes of dichorionic triplet pregnancy which reduced one monochorionic twin (group A) with trichorionic triplet pregnancy which reduced to twins (group B) were compared. Results 1) The proportion of MZT in 196 patients was 44.39% (87/196). There was a significant difference in the proportion of MZT among the in vitro fertilization (IVF) group, the intracytoplasmic sperm injection (ICSI) group, the frozen-thawed embryo transfer (FET) group and the artificial insemination (AIH / AID) group (P=0.001). There was also a significant difference between the assisted hatching (AH) group and the non-AH group (P=0.000). There was no significant difference in the proportion of MZT between the elderly (≥35 years) patients and non-elderly patients (P=0.330) and between the cleavage stage embryo transferred group and the blastocyst stage embryo transferred group (P=0.950). 2) The patients’ average age,the mean gestational age, the mean gestational age of newborns and the mean birth weight were similar. There was no significant difference in abortion rate, early abortion rate, late abortion rate, preterm birth rate, term birth rate, live birth rate, low birth weight rate and the incidence of neonatal birth defects and pregnancy complications (P>0.05). Conclusion The proportion of MZT was high in ART patients with multifetal pregnancy reduction. It should transform to a single embryo thansfer to reduce MZT incidence. There was no difference in clinical outcomes between group A and group B, multifetal pregnancy reduction of one monochorionic twin in dichorionic triplet pregnancy may be safe and feasible. Key words: Assisted reproductive techniques (ART); Multifetal pregnancy reduction; Monozygotic twins(MZT); Dichorionic triplet pregnancy; Clinical outcome