Association between Number of Formed Embryos, Embryo Morphology and Clinical Pregnancy Rate after Intracytoplasmic Sperm Injection

Abstract

Introduction Infertility has a high prevalence in the general population, affecting ∼ 5 to 15% of couples in reproductive age. The assisted reproduction techniques (ART) include in vitro manipulation of gametes and embryos and are an important treatment indicated to these couples. It is well accepted that the implantation rate is positively influenced by the morphology of transferred embryos. However, we question if, apart from the assessment of embryo morphology, the number of produced embryos per cycle is also related to pregnancy rates in the first fresh transfer cycle.

Purpose To evaluate the clinical pregnancy rate according to the number of formed embryos and the transfer of top quality embryos (TQEs).

Methods In a retrospective cohort study, between January 2011 and December 2012, we evaluated women who underwent intracytoplasmic sperm injection (ICSI), aged < 40 years, and with at least 1 formed embryo fresh transferred in cleavage stage. These women were stratified into 3 groups according to the number of formed embryos (1 embryo, 2–3 and ≥ 4 embryos). Each group was divided into 2 subgroups according to the presence or not of at least 1 transferred TQE (1 with TQE; 1 without TQE; 2–3 with TQE, 2–3 without TQE; ≥ 4 with TQE; ≥ 4 without TQE). The clinical pregnancy rates were compared in each subgroup based on the presence or absence of at least one transferred TQE.

Results During the study period, 636 women had at least one embryo to be transferred in the first fresh cycle (17.8% had 1 formed embryo [32.7% with TQE versus 67.3% without TQE], 42.1% of women had 2–3 formed embryos [55.6% with TQE versus 44.4% without TQE], and 40.1% of patients had ≥ 4 formed embryos [73.7% with TQE versus 26.3% without TQE]). The clinical pregnancy rate was significantly higher in the subgroup with ≥ 4 formed embryos with at least 1 transfered TQE (45.2%) compared with the subgroup without TQE (28.4%).

Conclusions Having at least two available embryos and at least one TQE for embryo transfer are predictors of the pregnancy rates.

Resumo

Introdução A infertilidade tem uma alta prevalência na população geral, afetando ∼ 5 a 15% dos casais em idade reprodutiva. As técnicas de reprodução assistida (TRA) incluem a manipulação in vitro de gametas e embriões e são um importante tratamento indicado para esses casais. Sabe-se que a taxa de implantação é positivamente influenciada pela morfologia dos embriões transferidos. No entanto, questiona-se, se além da avaliação da morfologia do embrião, o número de embriões produzidos por ciclo também está relacionado com as taxas de gravidez do primeiro ciclo de transferência fresco.

Objetivo Avaliar a taxa de gravidez clínica de acordo com o número de embriões formados e a transferência de embrião com ótima morfologia (EOM).

Métodos Em um estudo de coorte retrospectivo, entre janeiro de 2011 e dezembro de 2012, avaliamos mulheres submetidas a ICSI com idade < 40 anos e com pelo menos um embrião formado e transferido a fresco em estágio de clivagem. Estas mulheres foram estratificadas em 3 grupos de acordo com o número de embriões formados (1 embrião, 2–3 e ≥ 4 embriões). Cada grupo foi subdividido em 2 subgrupos de acordo com a presença ou não de EOM transferido (1 com EOM; 1 sem EOM; 2–3 com EOM; 2–3 sem EOM; ≥ 4 com EOM; ≥ 4 sem EOM). As taxas de gravidez clínica foram comparadas em cada subgrupo segundo a presença ou não de pelo menos um EOM transferido.

Resultados Durante o período do estudo, 636 mulheres tiveram pelo menos 1 embrião para ser transferido no primeiro ciclo a fresco (17,8% possuíram 1 embrião formado [32,7% com EOM versus 67,3% sem EOM], 42,1% das mulheres apresentaram 2–3 embriões formados [55,6% com EOM versus 44,4% sem EOM], e 40,1% das pacientes formaram ≥ 4 embriões [73,7% com EOM versus 26,3% sem EOM]). A taxa de gravidez clínica foi significativamente maior no subgrupo com ≥ 4 embriões formados com transferência de pelo menos 1 EOM (45,2%) comparando-se ao subgrupo sem EOM (28,4%).

Conclusões Ter pelo menos dois embriões e pelo menos um EOM para transferência são fatores preditivos da taxa de gravidez.

Keywords

number of embryos - morphological evaluation - embryo quality - clinical pregnancy - ICSI

Palavras-chave

número de embriões - avaliação morfológica - qualidade embrionária - gravidez clínica - ICSI

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