AbstractSTUDY QUESTIONDo the attachment-related dimensionsAnxietyandAvoidanceand perceived partner and social support in recipients and donors influence disclosure to others about their involvement in donor-assisted conception (DAC)?SUMMARY ANSWERA higher global score on attachment Avoidance was associated with greater non-disclosure about involvement in DAC by participants to relationship-specific others.WHAT IS KNOWN ALREADYWithin the context of DAC, the topic of disclosure has been investigated in terms of the ‘if’, ‘when’, and the ‘how’ to disclose about circumstances of conception. Less focus, however, has been directed to investigating psychological theoretical frameworks that influence disclosure decisions to others, i.e. to whom information is disclosed and to what extent details are transparently revealed about the donor programme.STUDY DESIGN, SIZE, DURATIONThe study was of a cross-sectional design and utilized a sample of 301 participants who were, or had been, involved in DAC, and were recruited across states of Australia. An online self-report questionnaire was completed between June 2014 and June 2017.PARTICIPANTS/MATERIALS, SETTING, METHODSEnglish speaking participants consisting of 209 female recipients and 92 donors (36 sperm; 48 egg; 8 embryo donors). Of the recipients, 104 had successfully conceived children via donated gametes (68 sperm, 23 eggs, 6 embryos, and 7 recipients where both gametes were donated from 2 donors to create the embryo). Participants anonymously completed an online questionnaire consisting of five sections: Demographics, Donor Conception and Disclosure Practices, the Experiences in Close Relationships-Relationships Structure, the Quality of Relationship Inventory, and the Multidimensional Scale of Perceived Social Support. Pearson correlations, independent samplest-tests, Chi-square, and ANOVA were used to explore the association between attachmentAnxietyandAvoidancescores and disclosure about involvement in a DAC programme to significant others (i.e. parents, siblings, in-laws, and friends).MAIN RESULTS AND THE ROLE OF CHANCECompared to published community cohort data, participants reported lower global scores on attachmentAnxietyandAvoidanceand high levels of romantic partner and social network support, suggestive of secure relationships in the overall study sample. A higher score on attachmentAvoidancewas associated with less disclosure to significant others in their social network (i.e. parents, siblings, in-laws, and close friends), even in the presence of strong partner support (partialr= −0.248,P= 0.005). Higher scores on attachmentAvoidancewere inversely associated with level of perceived partner and social network support (allP< 0.05). Irrespective of attachment scores, more than 90% of all participants agreed that a child born of DAC should be told about mode of conception.LIMITATIONS, REASONS FOR CAUTIONThis study utilized a cross-sectional design precluding causal inferences between dimensions of insecure attachment and disclosure practices. Participants were required to self-report on the quality of their relationships with the potential for social desirability respondent bias. The study’s self-selecting sample may limit generalization to participants who were dis-inclined to participate. Specifically, respondents who have anAvoidantattachment style, may have elected not to participate in the study.WIDER IMPLICATIONS OF THE FINDINGSGiven the increased use of biotechnology and digital facial recognition enabling self-discovery of the donor and the donor’s extended family, non-disclosure about involvement in DAC may have consequences. An‘Avoidant’attachment style is important to assess as a potential risk factor for non-disclosure about involvement in DAC across different relational contexts (e.g. close family members and friends). Fertility counsellors should consider introducing a measure of attachment screening as a pre-emptive psychoeducational strategy during donor implications counselling. This information could be used to offer patients insight into concerns they have about DAC disclosures to key important relationships, providing a target of clinical intervention.STUDY FUNDING/COMPETING INTEREST(S)No external funds were sought for this work. None of the authors have any competing interests to declare.TRIAL REGISTRATION NUMBERN/A.