P-592 The effect of ethnicity on ovarian stimulation outcomes of altruistic oocyte donors from the largest UK vitrified egg bank: a retrospective cohort study
Authors: Bodri D , Pataia V , Linara-Demakakou E , Kováts T , Vendola M , Wolska M , Nair S , Macklon N , Ahuja K 
Published: June 2022

Abstract

Study question
Are there differences in ovarian stimulation outcomes among different ethnicities in the largest UK vitrified oocyte donation programme?

Summary answer
No significant differences were observed in ovarian response between non-White and White ethnic donor groups. Only AMH and baseline AFC correlated well with ovarian response.

What is known already
Ethnic disparities in ART outcomes have received much attention recently. Studies based on national registries have reported inferior outcomes for South Asian and Black ethnicities undergoing non-donor IVF treatment. Ovarian response has also been reported to differ across ethnicities, which was attributed to genetic or environmental factors, but also ethnic differences in ovarian reserve markers and body weight. A few US studies have evaluated recipient outcomes in oocyte donation treatment and found lower success rates for Black recipients. So far, no large study has evaluated the effect of ethnicity on ovarian response in a large cohort of oocyte donors.

Study design, size, duration
All consecutive oocyte donation cycles (n = 1.421) from the UK’s largest, private vitrified egg bank between 2017 and 2021 were included in this retrospective cohort analysis. Donors underwent general health evaluation, ovarian reserve (AMH, AFC) and infectious disease screening. Ovarian stimulation with recFSH was commenced on cycle day 2-3, with starting doses ranging from 112.5-450 IU. GnRH antagonist was given from day 6, and final oocyte maturation was triggered with a GnRH agonist (0.5 ml buserelin).

Participants/materials, setting, methods
Altruistic oocyte donors (n = 1.027) were stratified according to ethnicity; White (77%), mixed (7.4%), Black (5.4%), South-Asian (4.1 %), other Asian (3.5%) and South American (2.2%). In a univariate analysis, Kruskal-Wallis test was applied to compare age, BMI, AMH between ethnic groups and total and mature oocyte number during treatment cycles. In a multi-variate analysis, the effect of ethnicity, age, BMI, AMH and baseline AFC was evaluated on the number of total and mature oocytes obtained.

Main results and the role of chance
Univariate analysis showed no difference between ethnic groups in BMI (total average:23.5±3.1) AMH (total average:29.5±16.0 pmol/L) whereas other Asians were older (30.5±4.6 years, p &lt; 0.001) and South Americans younger (24.4±4.7 years, p = 0.005) compared to Whites (27.1±4.6 years). The total number of eggs retrieved did not differ significantly between ethnic groups; White:19.6±9.1, mixed:19.6±9.0, Black:20.1±10.3, South-Asian:18±8.3, other Asian: 17.6±8.8 and South American:17.7±8.4, p = 0.24). The same applied to mature eggs obtained: White:14.2±7.1, mixed:13.9±7.2, Black:12.7±7.1, South-Asian:13.4±7.1, other Asian: 13±7.2, South American:12.8±7.1, p = 0.19). However, oocyte maturity rate was significantly lower in Black compared to White donors (64±19% vs 73±18%, p = 0.003). In a multivariate analysis, only baseline AFC (p &lt; 0.0001) and AMH (p &lt; 0.0001) correlated well with either the number of retrieved total or mature eggs.

Limitations, reasons for caution
Retrospective cohort studies might have inherent biases that make comparisons difficult. Slightly different inclusion criteria (age, AMH) for different ethnicities might have affected ovarian stimulation outcomes. The size of some subgroups was too low to yield statistically meaningful results. Some baseline donor variables were not included in our analysis.

Wider implications of the findings
Ovarian response outcomes were not substantially different across various ethnic groups of altruistic, UK oocyte donors. This study indicates that reported ethnic differences in IVF outcomes is unlikely to be due to response to ovarian stimulation. Donor egg programs can anticipate similar numbers of eggs irrespective of donor ethnicity.

Trial registration number
n/a