P-168 Follow-up survey of deliveries derived from Day 7 blastocysts

Abstract

Abstract Study question Does Day 7 blastocyst-transfer affect prognosis of babies born? Summary answer There was no effect on growth up to 3 years of age in babies from Day 7 blastocyst-derived births. What is known already Culture medium and technology have advanced, and the efficiency to culture up to the blastocyst stage in order to obtain viable embryos has increased dramatically. As a result, blastocyst transfer is associated with higher clinical pregnancy outcomes than cleavage transfer. In 1998, it was first reported that some embryos may develop into blastocysts on Day 7. However, there are few reports on neonatal outcomes from Day 7 blastocyst transfer. Therefore, the utility of Day 7 blastocysts is controversial. Study design, size, duration This was retrospective study which included 23 cases where there was a live birth after single embryo transfer of a Day 7-derived blastocyst. The incidence of birth defects, birth weight was recorded as well as a physical development survey. The height and weight were recorded in 10 children aged 18-months and 4 children aged 3 who responded to follow-up survey. The time period was from January 2013 to December 2021. Participants/materials, setting, methods Patient seeking fertility treatment at an established private IVF clinic. We compared the birth weight, and birth after 18-months and 3 years height and weight of children born to a Day 7 blastocyst with data from babies born from Day 5 and Day 6 derived blastocysts. Statistical significance was determined using Kruskal-Wallis test. Main results and the role of chance The incidence of birth defects was 2.4% (115/4828), 1.7% (16/954) and 0% (0/23) in the Day 5, Day 6 and Day 7 groups, respectively. The average birth weight of the Day 7 group was 3057+/-532 g, which was not significantly different from 3024+/-472 g and 3041+/-480 g in the Day 5 and Day 6 groups. The average height at 18-months, was 80.0+/-5.3 cm, 79.8+/-5.1 cm, 77.8+/-6.9 cm in the Day 5, Day 6 and Day 7 groups, respectively. The average weight at 18-months, was 10.5+/-1.2 kg, 10.4+/-1.1 kg, 10.5+/-1.4 kg. The average height at 3 years old, was 93.2+/-4.8 cm, 92.9+/-4.7 cm, 93.4+/-5.9 cm. The average weight at 3 years old, was 13.9+/-1.6 kg, 13.8+/-1.4 kg, 14.1+/-2.6 kg, respectively. There was no significant difference in average height and weight up-to the 3 years old follow-up survey. Limitations, reasons for caution The incidence of Day 7 blastocyst-transfer is low and the study was limited to cases of single blastocyst embryo transfer. The study was not separated by sex, because sample size was small. Wider implications of the findings There was no difference in growth up to a 3-year-old follow-up survey of the Day 7 blastocyst compared with the Day 5 and Day 6 groups. Transfer of a Day 7-derived blastocyst does not appear to affect infant development and should be considered in cases where blastocyst development is delayed. Trial registration number not applicable