Surrogates have a greater chance of being newly diagnosed with a mental illness during and after pregnancy than women who carry their own offspring, researchers have found.
In addition, regardless of how they conceived, women with a previous record of mental illness were found to have a higher risk of being diagnosed with such conditions during and after pregnancy than those without.
While laws around surrogates, or “gestational carriers”, vary around the world, the practice is booming. According to Global Market Insights, the market is expected to grow from $27.9bn (£20.8bn) in 2025 to $201.8bn (£150.2bn) in 2034.
“Our findings underscore the importance of adequate screening and counselling of potential gestational carriers before pregnancy about the possibility of a new-onset mental illness, or exacerbation of a prior mental illness during or after pregnancy,” said Dr Maria Velez, the first author of the research, from McGill University in Canada. “As well, the provision of support during and after pregnancy may be particularly important for gestational carriers.”
Writing in the journal Jama Network Open, Velez and colleagues report how they analysed data from 767,406 births in Ontario that occurred between 1 April 2012 and 31 March 2021.
Of these, 748,732 involved unassisted conceptions, 758 involved surrogacy, and the others involved IVF in mothers who carried their own babies. Velez said the vast majority of surrogacy cases in Canada involved the surrogate being unrelated to the child, meaning the surrogate’s eggs were not used in conception.
Among those excluded from this initial analysis were women with a record of mental illness prior to the estimated date of conception.
The team analysed the number of women in each group who received a diagnosis of a new-onset mental illness since the estimated date of conception, such as anxiety disorder, mood disorder, self-harm or psychosis.
These diagnoses occurred in 236 surrogates, 195,022 women who had an unassisted conception and 4,704 women who had received IVF.
After accounting for factors such as age, income, smoking and number of children, this corresponded to a 43% and 29% higher incidence rate of new mental illness per 100 people per year of follow-up in surrogates compared with women who had an unassisted conception or IVF, respectively.
For all three groups, mood or anxiety disorder was the most common diagnosis, while median time from conception to diagnosis was similar, at about two and a half years.
The researchers found the risk of new mental illness remained elevated in surrogates, but to a lesser degree, when compared with women who had an unassisted conception but no longer lived with their child a year after the birth.
“The finding might suggest that some gestational carriers may experience grief from relinquishing their newborn, like that described after adoption or removal of the child into foster care – something that needs further studies,” said Velez.
The team then carried out further analyses that included women with a previous record of mental illness and found all groups in this category had a higher rate of new-onset mental illness than those with no previous record. Despite Canada requiring would-be surrogates to undergo psychological assessments, the results revealed 19% of surrogates in the study had a documented diagnosis of mental illness before pregnancy.
The study follows previous research by the team that found surrogates were more likely to experience complications including severe postpartum haemorrhage and severe pre-eclampsia.
Dr Zaina Mahmoud, an expert on the socio-legal aspects of surrogacy at the University of Liverpool, in England, who was not involved in the work, said further research was needed to explore whether the greater risk of new mental illness in surrogates was down to the pregnancy itself, and the mechanisms at play.
“[The researchers are] not addressing why or how surrogates have these emotional trajectories,” she said, adding that the team had used very broad definitions of mental illness. “They hypothesise that grief from relinquishing the infant may contribute, but they don’t actually measure that grief.”
But Mahmoud backed the call for greater screening and support for potential surrogates, saying the work suggested support should last for more than two years after the birth. The studies “really highlight the need for robust information and consent procedures”, she said.