Infant attachment security similar across two dad, two mom, and heterosexual parent families
Attachment in families created through ART: results from the first study using the Strange Situation Procedure in same-sex and different-sex parent families. (Van Rijn-van Gelderen, 2025)
Van Rijn-van Gelderen, L., Ellis-Davies, K., Vecho, O., Rubio, B., Carone, N., Frau, C., Schiavetto, C., Runze, J., Jorgensen, T. D., Bos, H. M. W., & Lamb, M. E. (2025). Attachment in families created through assisted reproductive techniques: results from the first study using the Strange Situation Procedure in same-sex and different-sex parent families. Attachment & Human Development. Advance online publication. https://doi.org/10.1080/14616734.2025.2572578
Geographic Region: Netherlands, France, and United Kingdom
Research Question: Do attachment patterns differ among infants in same-sex male parent families (conceived via surrogacy), same-sex female parent families (conceived via donor insemination), and different-sex parent families (conceived via IVF)?
Design: This study employed an observational, cross-sectional design using the Strange Situation Procedure, a standardized, laboratory-based assessment of infant-parent attachment security. Data were collected from the longitudinal New Parents Study between 2013 and 2016. Children were assessed at approximately 12 months of age during university-based laboratory visits. Each child participated in the SSP twice on the same day, once with each parent, with order randomly determined.
Sample: 229 parent-child dyads from 115 families, drawn from the larger New Parents Study of 140 families. This comprised 65 parent-child dyads from same-sex male parent families (surrogacy and implied egg donors), 96 from same-sex female parent families (with sperm donors), and 64 from different-sex parent families (IVF). Families were distributed across three countries: United Kingdom (23%), Netherlands (34%), and France (43%). The vast majority of parents (84%) held college degrees or higher, most were married or in civil partnerships (83%), and most were employed full-time (58%). Most parents (97% in UK and Netherlands) identified as White. Families were recruited through specialized surrogacy lawyers, LGBTQ+ parent support groups, fertility clinics, and online platforms.
Key Findings
The study found that infants formed secure attachments with their parents at similar rates whether they were raised by two fathers (through surrogacy+implied egg donation), two mothers (through donor insemination), or a mother and father (through IVF).
Looking at all families together, about 54% of infants showed secure attachment relationships with their parents, which is nearly identical to the worldwide average of 52% found in studies of over 20,000 parent-child pairs. About 21% showed avoidant attachment, 14% showed ambivalent attachment, and 12% showed disorganized attachment.
Infants living in the Netherlands were more likely to be securely attached compared to infants in the United Kingdom, regardless of whether they had two fathers, two mothers, or a mother and father. This suggests that access to supportive social systems and contexts (e.g., parental leave policies, social support systems, and attitudes toward diverse families) may be more important than family structure itself.
Compared to worldwide data, this study found somewhat more infants with avoidant (21% vs. 15%) or ambivalent (14% vs. 10%) attachment patterns, but fewer with disorganized (12% vs. 24%) attachment.
Limitations: Convenience sampling may limit generalizability, as participating families may be more confident in their parenting and have more positive parent-child relationships. Suboptimal video quality in some recordings made subtle facial expressions crucial for disorganized coding harder to detect. Data on ethnic background and health were only collected for UK and Netherlands participants due to ethical restrictions in France. Very high educational attainment limits generalizability to lower socioeconomic families. The Strange Situation Procedure has been validated primarily with mother-child dyads.
Applications: Consider how contextual factors like parental leave policies, social support, and experiences of discrimination may affect caregiving and attachment, rather than family structure or donor type.
Funding Source: This research was supported by grants from the UK Economic and Social Research Council (ESRC; grant ES/K006150/1), the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO; grant 464-11-001), the French Agence Nationale de la Recherche (ANR; grant ANR-12-ORAR-00005–01), and the Nederlandse Wetenschapsagenda (grant NWA.1389.20.05), under the auspices of the Open Research Area (Application BO 3973/1–1).
Lead Author: Loes Van Rijn-van Gelderen is a researcher at the Research Institute of Child Development and Education at the University of Amsterdam in the Netherlands. A personal connection to donor conception was not disclosed.
Regulatory Context
The Netherlands has allowed identity-release donation since implementation of the Artificial Fertilisation Donor Information Act in 2004, which abolished donor anonymity. Same-sex female couples have had access to fertility treatment since 2005. A government-funded national register manages donor information, with donor-conceived individuals able to access identifying information at age 16. At the time of data collection (2013-2016), surrogacy was not officially available for same-sex male couples, requiring them to travel abroad (often to the US or Canada) and face administrative challenges for legal recognition of both parents.
The UK changed from anonymous to identifiable donation in 2005. Donor-conceived people conceived after April 1, 2005, can access donor identity information at age 18. The Human Fertilisation and Embryology Authority (HFEA) regulates fertility treatment. At the time of data collection, surrogacy was allowed in the UK.
France prohibited surrogacy during the data collection period (Law No. 94-653 of 1994), requiring same-sex male couples to travel abroad and face legal hurdles for parental recognition. In 2021, France expanded fertility treatment coverage to lesbians and single women and created laws to end anonymous donation, though these changes occurred after data collection. Same-sex female couples had access to fertility treatment at the time of the study.
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