‘Why have women not returned to use their frozen oocytes?’: a 5-year follow-up of women after planned oocyte cryopreservation

Abstract

Research question

What are the reproductive choices and retrospective reflections of women at least 4 years after planned oocyte cryopreservation (POC)?

Design

This was an internet survey, using the REDCap application, of women who underwent POC, at a single-centre university-affiliated IVF unit, 4–8 years before the survey. The questionnaire addressed reproductive choices and outcomes following POC.

Results

Seventy-nine women who underwent POC during 2011–2014 were invited to participate, and 70 (89%) responded. Mean age at cryopreservation was 37.1 ± 2.4 (range 30–41) years, mean age at study participation 42.6 ± 2.6 (range 35–48) years, and mean time from first cryopreservation cycle to study participation 5.5 ± 1.3 (range 4–8) years. The main retrospectively reported reason for POC was not wanting to become pregnant without a partner (59, 84%). During the follow-up period, 44 women (63%) attempted to conceive either naturally or by assisted reproductive technology using fresh or cryopreserved oocytes. Of those, 28 women achieved a live birth (64% of those who tried to conceive). Fourteen respondents (20% of all respondents) reported using their cryopreserved oocytes, and three (21%) achieved a birth using those oocytes. Fifteen women (34%) of those who tried to conceive used donor spermatozoa.

Conclusions

The most common reasons for not using frozen oocytes were achieving pregnancy without frozen oocytes or preferring not to have a child without a partner. A considerable proportion of women who had POC and were not interested in being a single parent by choice eventually try to conceive using donor spermatozoa several years later.

Introduction

While embryo cryopreservation has long been an integral part of assisted reproductive technology (ART), oocyte cryopreservation has lagged behind. The poor survival rates of oocytes that are thawed after using the ‘slow freezing’ technique initially precluded the widespread use of this clinical option (Iussig et al., 2019). However, the advent of vitrification made oocyte cryopreservation sufficiently effective and suitable for clinical use (Kuwayama et al., 2005), leading to a marked increase in the number of oocyte cryopreservation cycles (Johnston et al., 2021), as well as a massive rise in the number of healthy children born after oocyte cryopreservation (Noyes et al., 2009).

Oocyte vitrification has enabled both oocyte banking for donation, and fertility preservation (Cobo et al., 2018; Cobo et al., 2020; Seshadri et al., 2018). One unique application of oocyte vitrification is for women who wish to address an age-related fertility decline, once referred to as ‘social’ freezing, but more recently termed ‘planned’ freezing (Ethics Committee of the American Society for Reproductive Medicine, 2018).

Planned oocyte cryopreservation (POC) appears to be a reasonable option for women in their thirties who are not currently interested in having children but who wish to maintain a chance of future pregnancy using their own oocytes (Cobo and García-Velasco, 2016; Homburg et al., 2009; Molloy et al., 2009). While in 2004 the European Society for Human Reproduction and Embryology (ESHRE) advised against oocyte cryopreservation for non-medical (social) reasons (The ESHRE Task Force on Ethics and Law, 2004), in 2012 ESHRE endorsed social oocyte cryopreservation (Dondorp et al., 2012). In 2012, the American Society for Reproductive Medicine declared medical oocyte cryopreservation was no longer an experimental procedure but advised against social oocyte cryopreservation (American Society for Reproductive Medicine, 2013), and in 2018 it endorsed social oocyte cryopreservation (Ethics Committee of the American Society for Reproductive Medicine, 2018).

POC has been available for the last decade yet reports on clinical outcomes to date are mainly limited by small sample size (Balkenende et al., 2018; Gürtin et al., 2019; Hammarberg et al., 2017; Hodes-Wertz et al., 2013; Inhorn et al., 2018b; Jones et al., 2020; Wafi et al., 2020; Wennberg et al., 2019; Yee et al., 2020). There is only one large study reported in the literature (Cobo et al., 2018). The lack of reported large-scale results is due to the relatively recent uptake of oocyte cryopreservation. This has led to relatively short follow-up periods in previous studies and is coupled with the low utilization rate of vitrified oocytes (Balkenende et al., 2018; Cobo et al., 2018; Gürtin et al., 2019; Hammarberg et al., 2017; Hodes-Wertz et al., 2013; Jones et al., 2020; Wafi et al., 2020; Yee et al., 2020). Follow-up studies on women who underwent POC show that 20–48% tried to conceive naturally or by ART after POC, in most cases without using their cryopreserved oocytes (Balkenende et al., 2018; Hammarberg et al., 2017; Hodes-Wertz et al., 2013; Wafi et al., 2020). The rationale for the low utilization rate of cryopreserved oocytes was women still preferring not to be a single parent (Hammarberg et al., 2017).

Current follow-up studies are limited by both short follow-up periods after cryopreservation (2–3 years, with the exception of the study by Wafi and collections, which was 4.5 ± 2.4 years) and a relatively young age – 40 years or younger – at the time of survey (Baldwin et al., 2015; Balkenende et al., 2018; Hammarberg et al., 2017; Hodes-Wertz et al., 2013; Jones et al., 2020; Wafi et al., 2020; Wennberg et al., 2019; Yee et al., 2020). This means that women have not yet exhausted their fertility potential using their current oocyte pool, and thus may be less likely to turn to their cryopreserved oocytes. Furthermore, previously published reports do not distinguish between women who had recently had their oocytes cryopreserved (e.g. 1 or 2 years before reporting outcomes) versus those who underwent oocyte cryopreservation much earlier.

The present study aimed to describe the reproductive choices and retrospective reflections of women who underwent POC at the authors’ centre at least 4 years after POC, and to try to understand the motivation for these choices.