More than the oocyte source, egg donors as patients: a national picture of United States egg donors

Abstract

Purpose

To characterize national oocyte donation practice patterns from the perspective of individual donors rather than of recipients.

Methods

Retrospective cohort including all donor oocyte retrievals and transfers reported to SARTCORS in 2016 and 2017 in the USA. Primary outcomes include characteristics of oocyte donors and of donor oocyte cycles. Secondary outcomes include overall pregnancy rates, elective single embryo transfer (eSET) rates, and perinatal outcomes among donor oocyte recipient transfers.

Results

During the study period, 49,193 donor oocyte retrievals were performed, of which the largest proportion were in the Western US. For all reported retrievals, there were 17,099 unique donors, each of whom underwent an average of 2.4 retrievals (range 1–22). Average donor age was 26.3 years (range 18–48). On average, 24.6 oocytes (SD 12.4) were retrieved each cycle, ranging from 0 to 102. Among 37,657 donor oocyte recipient transfers, 20,159 (53.5%) involved eSET, and 17,725 (47.1%) resulted in live birth. Miscarriage rates were 17.5%, and good perinatal outcome (GPO), defined as full-term normal birthweight delivery, was more likely among singleton (75.7%) than multiple (23.8%) pregnancies.

Conclusion

The average number of retrievals that donors underwent and oocyte yield mirrored national guidelines; however outliers, exist that may unnecessarily increase donor risk. Additionally, among resultant donor transfers, 46.5% transferred more than one embryo despite national recommendations for eSET. The significantly higher likelihood of GPO among singleton pregnancies points to the need to further increase donor recipient eSET rates.

Introduction

The use of donor oocytes in vitro fertilization (IVF) has grown increasingly common; live birth rates and perinatal outcomes of resultant pregnancies continue to improve as elective single embryo transfer (eSET) rates increase [1]. While large cohort studies have evaluated outcomes among donor oocyte recipients [1–3], few studies have focused on individual donor characteristics. Although there has been a recent focus on donor health, prior to 2016, oocyte donors were not tracked individually, making large-scale national studies impossible.

While some suggest that a national donor registry would allow for improved donor safety [4] and surveillance, others contend that donor tracking impinges on donor privacy [5]. As a result, the majority of oocyte donor studies is recipient-level analyses, resulting in an exclusion of cycles in which donor oocytes are cryopreserved or banked for future use and an inability to quantify an individual donor’s contribution to multiple clinics. National American Society of Reproductive Medicine (ASRM) guidelines recommend limiting oocyte donation to no more than six total retrievals [6].

We use SARTCORS, a national surveillance system, to characterize oocyte donation patterns in 2016 and 2017 from the perspective of individual donors rather than of recipients in the USA.

Materials and methods

The analysis included all donor oocyte retrievals performed in the USA between 2016 and 2017 that were reported to SARTCORS. Donor and cycle characteristics were tabulated for cycles for which the resulting oocytes were either “fresh,” fertilized upon retrieval without cryopreservation, or “frozen,” cryopreserved, possibly in an egg bank, for future use. Collected variables for oocyte donors include geographic location, age, gonadotropin dose, stimulation protocol, ovulation trigger type, and oocyte yield. No other demographic or cycle level characteristics are reported to SARTCORS. Prior to 2016, donors did not have a unique donor identifier; a donor retrieval was only captured retrospectively if the oocytes were used in a subsequent recipient transfer. Beginning in 2016, donor retrievals in which oocytes are frozen and not transferred are captured and attributed to a donor as a unique individual, with a unique donor identification number. In theory, all ART retrievals performed at SART member clinics should be reported to SARTCORS. This includes retrievals performed for an individual clinic’s donor program and also those performed on behalf of a donor egg bank.

In addition to analysis at the level of the donor retrieval, an analysis of all reported resultant fresh and frozen donor transfers in recipients that occurred between 2016 and 2017 was performed to determine overall elective single embryo transfer (eSET) utilization and subsequent birth outcomes such live birth rate per transfer, miscarriage rate per pregnancy, and likelihood of good perinatal outcome, GPO, (delivery at > 37 weeks and > 2500 grams) among singleton and twin pregnancies.

Summary statistics were calculated for measures of interest. Continuous variables are represented as means, standard deviations, and five-number summaries. Categorical variables are represented by counts and percentages. Analyses were conducted using SAS 9.4. The study was deemed exempt by Emory IRB.

Results

During the study period, 49,193 donor oocyte retrievals are performed in the USA (Table 1). The largest proportion are in the West, followed by the South, Northeast, and Midwest (Fig. 1). For all reported retrievals, there were 17,099 unique donors, each of whom underwent an average of 2.4 retrievals (range 1–22, standard deviation (SD) 2.4). Average donor age was 26.3 years (range 18–48, SD 3.6).

Table 1.

Donor personal and cycle characteristics per donor egg retrieval in the USA for frozen and fresh oocytes, 2016–2017

Donor retrieval characteristics	Frozen oocytes	Fresh oocytes	Total
Total number of donor retrievals	32,665	16,528	49,193
Geographic location of donor retrieval
West (total number of retrievals, %)			16,414 (33.4%)
South (total number of retrievals, %)			13,899 (28.3%)
Northeast (total number of retrievals, %)			12,480 (25.4%)
Midwest (total number of retrievals, %)			6,357 (25.4%)
Total number of unique identified donors	5,555	11,544	17,099
Number of retrievals per donor; mean (sd)	2.7 (2.8)	2.3 (2.1)	2.4 (2.4)
Number of retrievals per donor; min, q1, med, q3, max	1, 1, 2, 3, 22	1, 1, 1, 3, 22	1, 1, 1, 3, 22
Donor age; mean (sd)	26.1 (3.4)	26.4 (3.7)	26.3 (3.6)
Donor age; min, q1, med, q3, max	18, 24, 26, 28, 48	18, 24, 26, 29, 48	18, 24, 26, 28, 48
Donor stimulation characteristics
Total gonadotropin dose (IU); mean (sd)	2,570 (1080)	2,695 (1183)	2,617 (1121)
Total gonadotropin dose; min, q1, med, q3, max	0, 1825, 2400, 3075, 11625	0, 1875, 2475, 3300, 11625	0, 1859, 2450, 3150, 11625
Suppression protocol type
Agonist protocol (n, %)	2,447 (7.5%)	1,328 (8.0%)	3,775 (7.7%)
Antagonist protocol (n, %)	20,130 (61.6%)	12,019 (72.7%)	32,149 (65.4%)
Trigger type
hCG trigger (n, %)	2,947 (17.8%)	4,280 (13.1%)	7,227 (14.7%)
GnRh agonist trigger (n, %)	3,317 (20.1%)	4,586 (14.1%)	7,903 (16.1%)
hCG + GnRh agonist dual trigger (n, %)	1,991 (12.1%)	2,167 (6.6%)	4,158 (8.5%)
Missing	8,099 (49.0%)	20,989 (64.3%)	29,088 (59.2%)
Oocyte yield; mean (sd)	25.1 (12.7)	23.5 (11.7)	24.6 (12.4)
Oocyte yield; min, q1, med, q3, max	1, 16, 24, 32, 102	0, 15, 22, 30, 99	0, 16, 23, 31, 102

Fig. 1.

Number and proportion of donor oocyte retrievals performed by region of the USA, 2016–2017

With regard to ovarian stimulation, GnRH antagonists were most commonly used for LH surge suppression (65.4%), and GnRH agonists were the most common oocyte maturation trigger mechanism. Mean total gonadotropin dose was 2,617IUs (SD 1121). On average, 24.6 oocytes (SD 12.4) were retrieved each cycle, ranging from 0 to 102.

Among 37,657 donor oocyte recipient transfers, 20,159 (53.5%) involved eSET, and 17,725 (47.1%) resulted in live birth (Table 2). Miscarriage rates were 17.5%, and good perinatal outcome (GPO), defined as full-term normal birthweight delivery, was more likely among singleton (75.7%) than multiple (23.8%) pregnancies.

Table 2.

Cycle characteristics and pregnancy outcomes per donor egg transfer in the USA for frozen and fresh oocytes, 2016–2017

	Total (fresh + frozen eggs)
Donor recipient transfer characteristics	Number	Percentage
Total number of donor recipient transfers (fresh + frozen)	37,657
Elective single embryo transfer (eSET)	20,159	53.5%
Pregnancy outcomes
Among transfers	37,657
Live birth (> 20 weeks)	17,725	47.1%
Among pregnancies	21,494
Miscarriage	3,769	17.5%
Singleton	14,767	68.7%
Good perinatal outcome (> 37 weeks, > 2500 g)	11,179	75.7%
Twins or greater	2,958	13.8%
Good perinatal outcome (> 37 weeks, > 2500 g)	704	23.8%

Discussion

Approximately 7.5% of all IVF cycles involve donor oocytes [7]. While the average donor retrieval number and oocyte yield mirrored national guidelines, outliers exist. Additionally, while live birth rates among donor recipient transfers are reassuring, 46.5% of transfers involved transfer of more than one embryo despite national recommendations for eSET.

On average, donors underwent 2.4 retrievals and produced 26.3 oocytes per retrieval, a retrieval frequency and oocyte yield comparable to a young infertility patient with normal ovarian reserve but greater than that of an average infertility patient. To date, evidence does not suggest that oocyte donation is associated with short- or long-term risk [6], or that it impacts residual ovarian reserve or recipient transfer outcomes [8–10]. Nonetheless, the outliers, donors undergoing a high number of retrievals, some with very high oocyte yields, raise concern regarding aggressive ovarian stimulation, which may unnecessarily increase donor risk. There are also other hypothetical repercussions of very active donors; with an average oocyte yield of 26.3 and retrieval number of 2.4, it is plausible that each donor may be producing an average of over 60 oocytes. This could potentially result in the subsequent birth of 2–3 biologically related offspring if every 6–8 oocytes yields one blastocyst embryo with an approximately 50% chance of live birth [11]. For donors who go through multiple retrievals and/or have high oocyte yields, these numbers could be much higher.

Importantly, of the resultant donor oocyte recipient transfers, 46.5% involved the transfer of more than one embryo despite national recommendations for eSET for donor oocyte recipients [12]. While this reflects an improvement in compliance with recommendations since a previous study of cycles in 2011 and 2012 pointed to the discrepancy [13], there remains tremendous room for improvement in maximizing the likelihood of singleton donor oocyte pregnancies which, in turn, increases the probability of a good perinatal outcome, which was notably more likely among singleton pregnancies.

While this study is strengthened by its inclusion of donors from infertility clinics around the country and the characterization of donors as patients, it is limited by the lack of reported cycles by some egg banks, the restriction of the study to 2 years of available data, and the lack of collection of donor demographic information such as race/ethnicity and body mass index. The use of a single donor ID across practices and expansion of mandated reporting to include additional donor demographics and retrievals performed by egg banks would improve knowledge about total number of resulting children per donor and impact of donating oocytes on the women who allow others to build families.

Conclusion

As both the annual number of donor oocyte retrievals and the number of donor egg banks continue to increase, the characterization of donor cycles has become more important. An improved system of donor surveillance, which could be as simple as encouraging all egg banks to participate in national reporting, has the potential to provide added reassurance regarding the safety of oocyte donation.

Funding

This study was supported in part by the University of Iowa Institute for Clinical and Translational Science, which is granted with Clinical and Translational Science Award funds from the National Institutes of Health (UL1TR002537).

Declarations

Ethics approval

Deemed exempt by Emory IRB

Conflicts of interest

Not applicable