Abstract
BackgroundDespite limited information on neonatal safety, the transfer of frozen-thawed cleavage-stage embryos with blastomere loss is common in women undergoing in vitro fertilization. We aimed to evaluate the pregnancy outcomes and safety of frozen-thawed cleavage-stage embryos with blastomere loss.MethodsThis prospective, multicenter, cohort study included all frozen-thawed cleavage-stage embryo transfer (FET) cycles between 2002 and 2012. Pregnancy outcomes and subsequent neonatal outcomes were compared between FET cycles with intact embryos and those with blastomere loss.ResultsA total of 12,105 FET cycles were included in the analysis (2259 cycles in the blastomere loss group and 9846 cycles in the intact embryo group). The blastomere loss group showed significantly poorer outcomes with respect to implantation, pregnancy, and live birth rates than the intact embryo group. However, following embryo implantation, the two groups were similar with respect to live birth rates per clinical pregnancy. Among multiple pregnancies (4229 neonates), neonates from the blastomere loss group were at an increased risk of being small for gestational age (aOR = 1.50, 95% CI 1.00–2.25) compared to those from the intact group. A similar trend was observed among singletons (aOR = 1.84, 95% CI 0.99–3.37). No associations were found between blastomere loss and the subsequent occurrence of congenital anomalies or neonatal mortality. However, neonates from the blastomere loss group were at an increased risk of transient tachypnea of the newborn (aOR = 5.21, 95% CI 2.42–11.22).ConclusionsThe transfer of embryos with blastomere loss is associated with reduced conception rates. Once the damaged embryos have implanted, pregnancies appear to have the same probability of progressing to live birth but with an increased risk of small for gestational age neonates and transient tachypnea of the newborn.Study registrationThis study was retrospectively registered at Chinese Clinical Trial Registry. Registration number: ChiCTR-OOC-16007753. Registration date: 13 January 2016.
Highlights
Despite limited information on neonatal safety, the transfer of frozen-thawed cleavage-stage embryos with blastomere loss is common in women undergoing in vitro fertilization
After excluding 253 transfer cycles that were lost to follow-up or in patients who refused to participate, a total of 12,105 transfer cycles were included in the analysis (9846 transfer cycles in the intact embryo group and 2259 transfer cycles in the blastomere loss group), with a follow-up rate of 98.0%
In this cohort study of 12,105 frozen cleavage-stage embryo transfer cycles, we found that embryo transfer with damaged embryos was associated with lower rates of implantation, clinical pregnancy, ongoing pregnancy, and live birth compared with intact embryo transfer
Summary
Despite limited information on neonatal safety, the transfer of frozen-thawed cleavage-stage embryos with blastomere loss is common in women undergoing in vitro fertilization. We aimed to evaluate the pregnancy outcomes and safety of frozen-thawed cleavage-stage embryos with blastomere loss. Embryo cryopreservation with subsequent frozen-thawed embryo transfer (FET) has been increasingly used in assisted reproductive technology since it was first reported in 1984 [1]. Findings are conflicting regarding perinatal outcomes following transfer cycles of cleavage-stage embryos with blastomere loss. Other studies have reported that blastomere loss might be associated with a reduction in the implantation rate, impaired in vitro development after thawing and impaired embryo survival following embryo transfer [9,10,11,12,13]. Embryos with blastomere loss can be transferred and can implant and subsequently develop, the safety for the offspring is a concern for researchers and clinicians
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