Study question: Does the quality of a single transferred embryo have an effect on the pregnancy outcome?
Summary answer: After adjusting for confounding maternal variables, poor embryo quality was not associated with adverse obstetric or perinatal outcome in this small pilot study.
What is already known: Embryo quality is a major predictor of the success of in vitro fertilization treatment and studies have demonstrated a strong association between embryo morphology, implantation and clinical pregnancy rates. However, the association with obstetric and perinatal outcomes has not been evaluated.
Study design, size and duration: This single center, retrospective cohort study included 1541 fresh single embryo transfers (SETs) using non-donor oocytes in women ≤40 years between December 2008 and 2012. We compared the cycle outcome and singleton live births resulting from the transfer of a single fresh good quality (Grade 2) embryo with those resulting from the transfer of a single poor quality (fair, Grade 3 or poor, Grade 4) embryo in the cleavage or blastocyst stages.
Participants/materials, setting, methods: The cycle outcome parameters were biochemical pregnancy and clinical intrauterine pregnancy. The pregnancy outcomes were live birth, miscarriages and stillbirths after 20 weeks of gestation. Among the live births, perinatal outcome parameters included birthweight, small for gestational age, preterm delivery, pre-eclampsia, placental abruption and neonatal complications. Covariates were maternal age, body mass index, smoking status, parity and gender of the baby.
Main results and role of chance: There were 1193 good quality SETs and 348 poor quality embryo transfers. SETs performed during the study period resulted in 563 pregnancies and 440 singleton births. There was a higher clinical pregnancy rate (41.5%) and live birth rate (32.3%) in the good quality embryo transfer group compared with that in the poor quality transfer group (19.2 and 15.5%, respectively; P < 0.0001). There was no significant difference in the miscarriage rate between the transfers of a single good or poor quality embryo. Multivariable logistic regression analyses for pregnancy complications revealed no increased risk of maternal or neonatal complications with the transfer of a poor quality embryo. There was no difference in the obstetric or perinatal outcome of the live births resulting from a good or poor quality embryo after stratification by day of transfer.
Limitations, reasons for caution: The main limitations of this study are the retrospective nature of the study, the relative subjectivity of embryo scoring and the small number of live births after transfer of poor quality embryos.
Wider implications of the findings: Our findings may be used to reassure women that transfer of a single poor quality embryo, whether a cleavage or a blastocyst, does not appear to be associated with increased risks of adverse obstetric and perinatal outcomes.
Study funding/competing interest (s): Only internal funding was used. There is no conflict of interest in relation to the study.