The development of embryo cryopreservation and frozen embryo transfer has been useful for allowing future pregnancy attempts and reducing the risk of multiple pregnancies by limiting the number of embryos transferred . However, as a result, an enormous supply of embryos in storage has been reported worldwide [2–4]. In Japan, an estimated 61,000 embryos remain cryopreserved in storage nationwide, 15 % stored without definite plans for usage . Most patients store their unused embryos; however, after a certain period, the patient needs to make a decision on the fate of frozen embryos.
The storage period varies amongst countries and institutions. The Japanese Society of Obstetrics and Gynecology (JSOG) regulates the storage limit “until the end of the woman’s reproductive life (without a definite age or clear definition)”  and most institutions in Japan have a set storage period due to maintenance and storage cost. At the time of cryopreservation, patients are obliged to give consent to embryo disposal when they cannot be contacted after a set period of storage and in the case of divorce or a death of a partner. At the end of the storage period, patients must choose between three options: continue storage by paying an additional cost, discard, or donate to research. JSOG prohibits embryo donation to other infertile persons or couples since it causes confusion in parent–child relationship and the child’s welfare needs to be most prioritized .
The emotional burden in making this decision has been reported previously by several studies [7–14], with evidence that the disposition preferences changed over time [7, 9, 13] and those more worried about their embryos had longer storage time or wanted to freeze them indefinitely [8, 11, 15]. Factors influencing the decision have been found. These include: conceptualization of the embryo [9, 10, 12, 14, 16–19]; confidence (trust) in medical science [14, 16, 20]; and the lack of acceptable options . In addition, gender difference [8, 21], and disagreement between couples  concerning these factors has been reported. However, the majority of these studies focused only on the decision to dispose, not having both options of continuing and discontinuing storage; some of such studies were in recognition of the laws limiting storage time [8–14]. Furthermore, most of these studies reported influential factors but the actual decision making process remains unclear.
Only a few conceptual models, helpful in understanding the actual process, have been reported, using a qualitative approach [14, 18, 19]. Provoost et al. showed the embryo disposition decision in 2 stages: first, considering donation to others for reproductive purposes; and, second, considering donation for science . Nachtigall et al. illustrated the 3 questions to reach a decision and conflict with partners was observed in relation to the decision about whether the embryos were to be used for conception . However, these studies included patients who have yet made their decision, so these models may not reflect the actual process of those making such decisions since many studies show that patients often change their decision at a later stage [7, 9, 13]. In addition, much of the data obtained were from couples, and some may have felt constrained to speak of their real feelings in the presence of their partner.
Socio-cultural and demographic factors such as religion, treatment period [8, 22], ethnicity [22, 23], income, marital status, and education have been reported as influential in terms of donation to research . Choudhary et al. found that ethnic minorities were less willing to donate their embryos to research  while, Jain and Missmer found that compared to Caucasians, and in particular Protestants, Asians and those practicing other religions overwhelmingly approved the use of embryos for stem cell research . In Japan, despite arguments that religious influence is weak and less burden is felt compared to western societies, it has been reported that cultural values towards the embryo, such as Motherhood ethics, causes emotional burden during in vitro fertilization (IVF) treatment . Therefore, it is unclear if the results of the past qualitative studies are applicable for Japanese patients having continued storage as an option.
It has been criticized in Japan that patients can hardly bring themselves to express their feelings about embryos in the clinical settings . Therefore, there is a need for effective counselling and informed consent methods developed for patients who have difficulties making decisions about the fate of their frozen embryos. Hence, an understanding of the psychological processes of patients with different socio-cultural backgrounds that influence the decision is required. We therefore conducted a qualitative interview study of Japanese infertile women who have just made a decision concerning their embryos. This study aims to construct a conceptual decision-making model and to identify the socio-cultural factors that influence these decisions.