Blastocyst culture of non-top-quality cleavage embryos may increase the risk of anembryonic pregnancy following in vitro fertilization: a retrospective cohort study

BACKGROUND: Anembryonic pregnancy (AP) is the most severe dysmorphogenesis of human embryo development and a frequent presentation of early pregnancy loss (EPL). Studies have analyzed the association between assisted reproductive technologies (ART) and EPL. However, the specific relationship between ART and AP has not been fully elucidated. Several studies suggested that non-genomic anomalies might be related to AP and ART might increase the risk of epigenetic changes, thus possibly detecting some associations between ART and AP. Our study aims to find out any possible risk factors of AP in ART treatments, and translate the results into clinical practice. METHODS: A retrospective cohort study was conducted in Nanfang Hospital. Data from 1,765 singleton pregnancies following fresh or frozen-thawed embryo transfer from January 2014 to December 2017 were collated with the inclusion of EPLs and normal live births (NLB). Participants were divided into three groups: NLB (full-term birth with normal body weight infants), EPL (spontaneous pregnancy loss prior to 13 weeks gestation) with embryos (EE), and APs (embryonic pole was invisible in two consecutive ultrasound examinations). The basic characteristics of the patients and the association between ART-related variables and AP were analyzed using one-way analysis of variance (ANOVA) and multivariable logistic regression model, respectively. Products of conception (POC) from AP and EE patients received karyotype analysis using multiplex ligation-dependent probe amplification (MLPA). RESULTS: Blastocyst culture of non-top-quality cleavage stage embryos almost doubled the percentage of AP in EPL (45.9% vs. 24.4%, P=0.037), and the normal euploid rate was significantly higher in the AP group (50.5% vs. 32.3%, P=0.003). Using multivariable logistic regression model, we found that blastocyst transfer and advanced maternal age might be risk factors for AP (OR >1, P<0.05). Deceased β-HCG level might indicate its occurrence (OR <1, P<0.001) while CoQ10 supplementation might be a protective factor (OR <1, P<0.001). CONCLUSIONS: The occurrence of AP may be due to epigenetic abnormalities associated with advanced maternal age and extended in vitro embryo culture, while CoQ10 supplementation may be a potential method in preventing AP. Future multi-center prospective cohort studies should be conducted to verify these results.