Relationships between mothers and children in families formed by shared biological motherhood.

STUDY QUESTION: Does shared biological motherhood, in which a woman gives birth to the genetic child of her female partner, result in more positive mother-child relationships than donor insemination, in which only one mother is biologically related to the child?

SUMMARY ANSWER: Mothers in both family types showed high levels of bonding with their children and viewed their relationship with their child positively.

WHAT IS KNOWN ALREADY: There is some evidence of feelings of inequality regarding their relationship with their child between biological and non-biological mothers in lesbian mother families formed by donor insemination, with a qualitative longitudinal study showing a tendency for children to form stronger bonds with their biological than their non-biological mother.

STUDY DESIGN, SIZE, DURATION: Thirty lesbian mother families created through shared biological motherhood were compared with 30 lesbian mother families formed by donor-IVF. All families had two mothers who both participated in the study, and the children were aged from infancy up to 8 years old. Data collection took place over 20 months beginning in December 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Each mother in the family was interviewed separately using the Parent Development Interview (PDI), a reliable and valid measure of the nature of the parent's emotional bond with their child. The interviews were transcribed verbatim and coded separately by one of two trained researchers who were unaware of the child's family type. The interview produces 13 variables that relate to the parent's representations of themselves as a parent, 5 variables that relate to the parent's representations of the child, and a global variable that assesses the extent to which the parent can reflect on the child and their relationship.

MAIN RESULTS AND THE ROLE OF CHANCE: Families formed through shared biological parenthood did not differ from families created by donor-IVF in terms of the quality of mothers' relationships with their children as assessed by the PDI. Neither were differences identified between birth mothers and non-birth mothers across the entire sample, or between gestational and genetic mothers within the families formed by shared biological parenthood. Multivariate analyses were conducted to minimize the role of chance.

LIMITATIONS, REASONS FOR CAUTION: Ideally, larger samples of families and a narrower age range of children would have been studied, but this was not possible as we were reliant on the small number of families formed through shared biological motherhood in the UK when the study began. To maintain the anonymity of the families, it was not possible to request information from the clinic that may have shed light on differences between those who responded to the request to participate and those who did not.

WIDER IMPLICATIONS OF THE FINDINGS: The findings show that shared biological motherhood is a positive option for lesbian couples who wish to have a more equal biological relationship to their children. One type of biological connection does not appear to have a greater influence on the quality of parent-child relationships than the other.

STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the Economic and Social Research Council (ESRC) grant ES/S001611/1. KA is Director, and NM is Medical Director, of the London Women's Clinic. The remaining authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER: N/A.