The effect of transferring a poor-quality embryo together with a good-quality embryo on the singleton birth weight: A retrospective cohort study.

Background: Embryo quality may affect birth weight among neonates born through assisted reproductive technology. There are very limited studies assessing the adverse effect of transferring a poor-quality embryo with a good-quality one on neonatal outcomes. Objective: The aim of this study was to evaluate the effect of double embryo transfer (DET) with one good-quality embryo (GQE) plus a poor-quality one on the birth weight of newborns conceived by in vitro fertilization in both fresh and frozen-thawed embryo transfer cycles. Materials and Methods: This study was conducted at Yazd Reproductive Sciences Institute, Yazd, Iran. A total of 626 women were classified into three groups according to the embryo quality: single embryo transfer with a GQE (group A); DET using two GQEs (group B); and DET using one good-quality and one poor-quality embryo (group C). The primary outcome was singleton birth weight which was compared between the three groups among fresh and frozen-embryo transfer cycles. A comparative analysis was also performed regarding the effect of vitrification procedures on neonatal birth weight within each of the three embryo quality-based groups. Results: The mean birth weight and the rate of preterm birth were similar between the three groups (p = 0.45 and 0.32, respectively). There were also no significant differences found in the vitrification comparative analysis between and within the groups with regard to birth weight. Conclusion: Our results showed that a poor-quality embryo did not have a significant influence on a good-quality one regarding neonatal birth weight when transferred together.