JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):146
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263783

P-134. Impact of maternal age on blastocyst formation day in assisted reproduction cycles

Gabriela Melo Souza¹, Julia Gonçalves Fella¹, Diana Caroline da Silva Bastos¹, Rafaela Aguiar¹, Larissa Paola Coelho Pedroso¹, Eliana Junko Morita¹, Raquel Mitie Koike¹, Enoch Quindere de Sa Barreto¹

¹ CITI MEDICINA REPRODUTIVA - São Paulo - SP - Brasil

Objective: To evaluate the relationship between maternal age and blastocyst formation day in assisted reproduction cycles.
Methods: Retrospective study conducted at our Reproductive Medicine Center, including ICSI (intracytoplasmic sperm injection) cycles with fresh and thawed eggs from January 2022 to July 2025. The cycles were divided according to maternal age into three groups: ≤34 years, 35–39 years, and ≥40 years. Only cycles with blastocyst culture were considered. The formation rates on days 5 (D5), 6 (D6), and 7 (D7) were calculated as the proportion of cultured embryos that reached the blastocyst stage on each day in relation to the number of fertilized eggs. Statistical analysis was performed using the ANOVA test, considering p<0.05 as significant.
Results: A total of 672 cycles were included in the study: 140 from patients aged up to 34 years, 254 from patients aged between 35 and 39 years, and 278 from patients aged 40 years or older. It was observed that the blastocyst formation rate on D5 was significantly higher in the ≤34 years group (39.7%) compared to the 35–39 years (32.4%) and ≥40 years (29.0%) groups (p=0.0001). The rates on days 6 and 7 did not differ significantly. On D6, the rates were 16.8%, 20.8%, and 18.7% (p=0.149), and on D7, they were 1.91%, 2.76%, and 2.58% (p=0.268) for the ≤34 years, 35–39 years, and ≥40 years groups, respectively. However, there was a tendency for a higher proportion of blastocysts to form on D6 and D7 in patients over 35 years of age, compared to patients up to 34 years of age.
Conclusion: Our results indicate that advanced maternal age is associated with a significant reduction in the rate of blastocyst formation on the fifth day. In addition, monitoring development until the seventh day may have a positive outcome for older patients by increasing the number of blastocysts. These findings highlight the importance of considering maternal age and its impact on embryonic development in order to increase blastocyst formation.