P-182 The impact of ethnic differences on embryo morphokinetics and clinical outcomes: the importance of racial admixture
Authors: Iaconelli C , Braga D , Setti A , Guilherme P , Iaconelli A. , Borges Junior E 
Published: June 2022

Abstract

Study question
Can ethnic differences affect embryo morphokinetics and clinical outcomes in a time-lapse imaging (TLI) embryo culture system?

Summary answer
Embryos from Mestizos develop faster and have a higher implantation rate than those from Caucasian and Asian patients.

What is known already
Over the past decades, the use of assisted reproductive technology (ART) has made pregnancy possible for many infertile couples. However, certain infertile couples exhaust all forms of ART, without achieving success. Differences in treatment success have been described as varying by race and ethnicity. In fact, it has been reported that ethnicity is a major determinant of ART outcome as indicated by significantly lower live birth rates in some ethnic minority groups, however the precise reason for this fact remains unknown. TLI may allow the identification of morphokinetics events potentially affected by ethnicity, which may impact embryo development and implantation.

Study design, size, duration
This historical cohort study enrolled 3,304 embryos from 466 patients undergoing ICSI cycles from Feb/2019 to Ago/2021. Female patients were split into groups according to the patient’s ethnicity: (i) Caucasian (356 patients and 2556 embryos), Mestizo (82 patients and 592 embryos), and Asian (156 patients and 28 embryos). Embryos were cultured in a TLI incubation system and morphokinetics factors and clinical outcomes were compared between the groups using generalized linear models followed by Bonferroni post-hoc.

Participants/materials, setting, methods
Recorded kinetic markers were timing to pronuclei appearance and fading (tPNa and tPNf), timing to two (t2), three (t3), four (t4), five (t5), six (t6), seven (t7), and eight cells (t8), and timing to morulae (tM), start of blastulation (tSB) and blastulation (tB). Durations of second and third cell cycles (cc2 and cc3) and timing to complete synchronous divisions s1, s2, and s3 were calculated. Additionally, the known implantation data score (KIDScore) day-5 was recorded.

Main results and the role of chance
Embryos derived from Mestizo patients completed several key-point stages faster, followed by Caucasians, while Asiatic embryos were the slower ones. Mestizo presented shorter t6 (54.8 ± 0.92, 52.6 ± 0.20, 51.0 ± 0.42, for Asians, Caucasians, and Mestizos respectively, p &lt; 0.001), t7 (58.4 ± 1.05, 55.4 ± 0.22, 54.1 ± 0.45, for Asians, Caucasians, and Mestizos respectively, p &lt; 0.001), t8 (59.3 ± 1.2, 58.7 ± 0.24, 57.3 ± 0.49, for Asians, Caucasians, and Mestizos respectively, p = 0.019), tM (99.3 ± 2.1, 90.8 ± 0.37, 87.5 ± 0.79, for Asians, Caucasians, and Mestizos respectively, p &lt; 0.001), tsB (106.4 ± 1.9, 101.4.0 ± 0.54, 98.0 ± 1.4, for Asians, Caucasians, and Mestizos respectively, p &lt; 0.001), and tB (109.1 ± 0.31,116.2 ± 2.0, 106.0 ± 0.64, for Asians, Caucasians, and Mestizos respectively, p &lt; 0.001). In addition, the KIDScore-D5 ranked significantly higher for Mestizos, followed by Caucasians, while Asian patients presented the lower KIDScore-D5 (2.9 ± 0.27, 5.3 ± 0.1, 6.3 ± 0.4, p &lt; 0.001). Pregnancy (25.0 ± 4.9, 33.0 ± 13.2, 58.0 ± 11.5, p = 0.038) and implantation rates (30.0 ± 1.2, 16.3 ± 0.4, 50.0 ±1.5, p &lt; 0.001) were also highest among Mestizos, followed by Caucasians, whereas the Asian patients had the lowest rates.

Limitations, reasons for caution
The retrospective nature of the study and the small sample size may have biased the results.

Wider implications of the findings
Despite the increasing number of studies investigating the effect of ethnicity on ART outcomes, most of the literature has focused on White, Black and Asians. However, racial admixture has markedly increased, making attempts at strict racial categorisation confusing and out-dated. Apparently, miscegenation benefits embryonic development, which may impact clinical outcomes.

Trial registration number
Not applicable