The Science of Surrogacy, Thrust Into a Global Spotlight
It was after seeing a friend go through multiple miscarriages that Kristin Spaans decided to help. With two children of her own, the now 38-year-old offered to become a surrogate and carry her friend’s baby — for which her friend is paying her just under $13,000, she said, on the low-end as far as typical compensation goes.
The experience has not been without hiccups. Spaans needed a medical exemption to continue taking an SSRI for anxiety, and there were other delays. “Since surrogacy is such a process of trying to eliminate risk, they just take all the precautions,” she said.
But overall, the pregnancy is going smoothly, said Spaans, who is now 32 weeks along. “I haven’t had any feelings of wanting to keep it or wanting another one of my own,” she added. “That’s been really a relief.”
Kristin Spaans, pictured here at 20 weeks pregnant, offered to be a surrogate for a friend. Spaans says the pregnancy is going smoothly, and she’s now 32 weeks along.
Visual: Courtesy of Kristin Spaans
Surrogacy, when a woman carries and gives birth to another person’s child, is a process used largely by infertile couples, or gay or single men wanting to have children. (Most surrogates do not use their own eggs.) In recent years, it has attracted increased attention, both because of the perceived risks to surrogates’ mental and physical health, and concerns from feminists, religious, and political groups arguing that it commodifies women’s bodies.
In Europe, this has resulted in political pushback: In 2024, Italy criminalized traveling abroad for the practice and over the past two years the Spanish government asked universities to restrict educational information about surrogacy. In November 2025, the European Parliament condemned surrogacy in a non-binding resolution as part of its Gender Equality Strategy. While the U.S. has seen comparatively less opposition, some scholars are concerned that may change, particularly when it comes to backlash against gay families. And surrogacy has made the news recently as schemes take advantage of intended parents and would-be surrogates alike.
Last summer, surrogacy sparked debate again when the United Nations’ special rapporteur on violence against women and girls published a report that called for a global ban of the practice, claiming it exploited women and children and amounted to a violation of their human rights. The report, written by independent expert Reem Alsalem, said it drew on input from surrogates, parents, and medical experts, but it lambasted the limited academic research: “The Special Rapporteur also relied on reputable secondary sources, which were few, given their weaknesses.”
Although the UN can’t dictate policy on surrogacy, the guideline’s publication put a global spotlight on an already fraught issue.
The lack of large-scale empirical research may have created an environment for speculation and debate.
The limited data that is available, which mostly focuses on developed nations or those with regulations on surrogacy, presents a mixed picture. Qualitative studies have explored the emotional and psychological outcomes of surrogates, their families, and the children born through surrogacy, and indicate that concerns about mental health effects may be misplaced. But some recent quantitative analyses looking at pregnancy outcomes in gestational surrogacy, in which a surrogate carries a child that is not genetically theirs, suggest that it does pose physical risks.
Scientists, academics, and some intended parents agree that better data is needed. “We need more research. You know, we need to design better studies,” said Bryan McColgan, a writer and trained physician who is hoping to become a dad through surrogacy.
The lack of large-scale empirical research may have created an environment for speculation and debate. Surrogacy practices can also vary greatly country to country — particularly between Western nations and developing countries — making it difficult to study and form general conclusions on the practice. And while critics point to the small datasets on surrogacy, the relatively few families seeking it out mean that large-scale analyses are hard to conduct, according to Anja Pinborg, a Danish fertility specialist and a co-author of a systematic review, published online in 2015, that looked at outcomes of surrogate pregnancies compared with other forms of assisted reproduction and natural births. She does not encounter much research on surrogacy presented at conferences, said Pinborg.
Legal hurdles, too, can make studying cross-border surrogacy more difficult. As a result, many studies take the form of case reports, Pinborg added. Intended parents may obtain the eggs from a woman in one country and have them transferred to a surrogate in another, depending on their situation, finances, and the local regulations. “So it’s very few cases, and they are spread over many regions and many countries,” Pinborg said.
“So that is the challenge, I think, about surrogacy and to really try to do research in that area.”
Even though the number of people pursuing surrogacy is relatively small, the market has grown in recent years. In the U.S., embryo transfer cycles that used surrogates almost tripled between 2013 and 2022, the latest year for which data is available. The U.S. also offers one of the largest and, according to practitioners in the field, safest and most ethical markets due to state laws regulating surrogacy and suggested best practices, such as psychological screenings for surrogates and intended parents. Those conditions have helped attract surrogacy tourism from Europe. In the U.K., for example, about 500 children are born through surrogacy per year, half of whom were born abroad, most to U.S.-based surrogates.
“The overwhelming majority of these arrangements are really quite beautiful,” said Mary Riddle, a clinical psychologist specializing in reproductive health and a member of the committee that wrote the guidance on qualifications for fertility counselors published by the American Society for Reproductive Medicine. “When you talk to people afterwards, parents are so grateful, and the surrogates tend to really feel good about having done something good.” Still, relationships can break down or expectations be unmet, she said. Riddle recalled one situation where communication was poor: By the time the surrogate gave birth to a healthy baby, she and the intended parents were no longer speaking. “Things do go wrong sometimes.”
Such possibilities — of women being mentally or physically harmed through these arrangements — underly most of the opposition to the practice. For decades feminists and women’s health advocates have pointed to the potential for coercion or financial exploitation of women and her potential attachment to the child, fears exacerbated by disputes like the 1986 case of Baby M, in which a surrogate wanted to keep a baby that was genetically hers, and more recent scandals like when a California couple was revealed in August to have nearly two dozen children, most believed to have been born through surrogacy. (Reports of women being exploited and even held against their will have trailed the practice in developing countries, sometimes leading to bans.) Most research on surrogacy in Western countries focuses on child outcomes and the lived experiences of those going through surrogacy and doesn’t touch on some of these more ethically fraught questions, said Kirsty Horsey, a professor of law at Loughborough University in the U.K.
Several qualitative studies by British researchers have been done on the psychological impact of surrogacy on gestational carriers, although they were completed quite some time ago, said Pinborg. She called for more long-term qualitative studies into the lives of surrogates. Still studies from the U.K., where altruistic surrogacy — in which women don’t receive payment for the pregnancy beyond covering medical expenses — is legal, show that the practice largely has positive emotional outcomes for carriers and children. Sarah Norcross, director of Progress Educational Trust, a British charity, said that for intended parents going through stress and anxiety, such research is consoling. She recalled a gay man who “was really worried about the impact on the children and whether the children have been okay.” When he came across the work of Susan Golombok, a University of Cambridge academic who has published extensively in the field, showing “that the kids are all right, it was a massive reassurance to him,” she said.
For decades feminists and women’s health advocates have pointed to the potential for coercion or financial exploitation of women and her potential attachment to the child.
There have been other reassuring findings. A paper published in 2024 involving more than 200 surrogates in the U.S. found that 88 percent described their motivation for becoming surrogates as simply wanting to help others; the vast majority also felt satisfied with their family’s well-being after the surrogacy. (Its lead author, José Ángel Martínez-López, a professor at the University of Murcia in Spain, told Undark that he had turned to the U.S. to conduct the research because surrogacy is not legal in his own country.)
Martínez-López, who spoke through a translator, said his study included the biggest sample of surrogates surveyed to date in his field. The relatively large number of participants, most of whom were employed and had medium to high levels of education, made the data significant, he added.
In her report, Alsalem, the UN’s special rapporteur on violence against women and girls, cited Martínez-López’s study to note that “While there are some altruistic surrogates who are well educated and financially stable,” most come from poor backgrounds and lack capacity to speak up. Martínez-López said the UN report drew on input from feminist groups — which have campaigned against surrogacy in Spain — but ignored scholarly research. He worried that it could influence policy in Spain, which recently ordered its embassies not to recognize birth certificates of babies born through surrogacy abroad. The move is part of a crackdown on surrogacy, which the country’s leftwing governing party says exploits women.
Many other researchers in the field have expressed concern about the UN report. Marcin Smietana, a research fellow at Ca’ Foscari University of Venice and an affiliated lecturer in sociology at the University of Cambridge, has written papers exploring the dynamics between gay men and their surrogates. He noted that Alsalem mentioned only minimally the work of Golombok, the Cambridge academic who is also the author of an award-winning book, “Modern Families.” Part of her research has followed a few dozen families over about two decades. While some experts may criticize the types of studies that Golombok does as biased, Smietana wrote in an email, he disagrees and said the samples used are entirely adequate for psychological research. In an email, Golombok told Undark that in her work, she and her colleagues “went to great lengths” to reduce bias.
The UN rapporteur overlooked or minimized the value of such research, Smietana said, while drawing on sources that are not peer-reviewed: It is “extremely problematic and very fraught because it doesn’t really use research, or the research that it uses is used in an extremely selective way.”
In an email to Undark, Alsalem maintained her position. In what she described as Golombok’s most widely cited longitudinal study, Alsalem referred to a drop from 42 families to 28 later on, and said that dropout rates are associated with negative experiences (although the number of families with children conceived naturally also fell over the study’s duration). Alsalem said she made her own “independent judgment about the strengths and weaknesses of the evidence presented — from a human rights perspective.”
Golombok told Undark by email that there was no evidence the families dropped out due to negative experiences of surrogacy. Many of the families could simply not be found, she said. She said she found it shocking that the UN, “so deliberately dismissed the findings of an in-depth study of a representative sample of surrogacy families that followed the children up from infancy to adulthood,” and added, “I think that the UN should do better than this!”
Any pregnancy inherently involves physical risk. Jenny Navis, a dentist in Portland, Oregon, acted as a surrogate for a heterosexual couple in 2022. She had already given birth to her own children, twins, by Cesarian section and wanted to experience a vaginal birth. Things were going smoothly until 32 weeks in, when she woke in the middle of the night and realized she already five and a half centimeters dilated. “Everything was fine until I ended up going into premature labor.”
Her earlier Caesarian scar ruptured, she recounted, causing her uterus and bladder to break open. The placenta separated from the uterus, putting the baby’s life at risk, though they ultimately both survived. “I definitely lost a lot of blood,” she recalled.
The UN report is “extremely problematic and very fraught because it doesn’t really use research, or the research that it uses is used in an extremely selective way.”
Navis’ experience runs in line with some of the research: A 2024 systematic review focused on obstetric outcomes found that surrogate pregnancies in which a woman carried an implanted egg “posed higher risks” than standard pregnancies, though the overall conclusion was unclear: Surrogate pregnancies were still less risky than non-surrogate pregnancies using assisted techniques, and a lack of patient history data meant the researchers could not link surrogacy with particular maternal outcomes. Meanwhile, an earlier systematic review from 2015 found that surrogate health outcomes were similar to mothers who used their own eggs through IVF, and most children born through surrogacy fared well. But it also noted that sample sizes were small and follow-up not always robust. And two recent studies led by a Canadian researcher have raised questions about the impact of the practice on gestational carriers’ mental and physical health.
One of those studies analyzed just over 860,000 births, 806 of which involved surrogates who carried eggs that were not their own. The team found that those women had a much higher risk of serious health complications during birth (7.8 percent, compared with 2.3 percent for women who conceived unassisted and 4.3 percent for women who bore their own children using IVF).
Bryan McColgan, a physician and author of the website Gay Dad Reporter, is hoping to become a dad through surrogacy.
Visual: Courtesy of Bryan McColgan
Alsalem cited those findings in her UN report. But some commentators urge nuance in interpreting the findings, noting that although the overall data set was large, the number of gestational carriers present in the study was relatively small, which could distort the results. The surrogates sampled also had higher rates of chronic hypertension than the rest of the group — which should have prevented them from acting as surrogates, according to McColgan, the physician and author of the website Gay Dad Reporter who began the surrogacy process with his husband three years ago, and plans to do an embryo transfer sometime this month. The research illuminated problems in Canada’s health care system, he wrote on his blog. “I strongly caution this study being extrapolated to gestational surrogacy in the U.S. where the standards and selection criteria are more strict.”
Another article using a similar dataset found that gestational carriers were more likely to be diagnosed with mental health conditions during and after pregnancy. They were also more likely to be obese or live in poorer neighborhoods. In both papers the number of surrogates was a tiny proportion of the overall sample, just 0.1 percent.
McColgan told Undark that, because of the small sample size, “the results that you can draw from that are not strong.” In his view, the most recent 2024 systematic review showed that “there are not enough well-designed studies to even be included in a meta-analysis,” he wrote by email.
Many of the experts and stakeholders that Undark interviewed had thoughts on how surrogacy could be improved, both for the surrogates themselves and for the children they bear. In the Netherlands, Laura Bosch, an independent researcher on children’s rights and formerly a legal adviser to the nongovernmental organization Defence for Children in the country, sits on the board of the government registry for donor-conceived kids, which allows teens to obtain information about their genetic origins once they are 16. The government is considering the establishment of a similar database for surrogate children, although the work and investment required are daunting, she said: “Just the concept of setting up such a registry, which will be mostly international moms — that’s going to be difficult.”
Men Having Babies, a U.S.-based nonprofit dedicated to supporting gay men seeking surrogacy, has published a framework outlining how to pursue surrogacy ethically, which they drew up after consulting with surrogates and other parties. It includes criminal background checks for prospective parents and informed consent on the part of surrogates.
Mary Riddle, a clinical psychologist, is a member of the American Society for Reproductive Medicine’s committee that wrote the guidance on qualifications for fertility counselors. Some of her studies on surrogacy have looked at the impacts on families of surrogates.
Visual: Courtesy of Mary Riddle
The American Society for Reproductive Medicine has also issued ethical and practical guidelines about best practices in surrogacy. The professional group advises that surrogates undergo psychological screening and be informed of all possible risks of surrogacy and pregnancy. But despite the availability of guidelines, Riddle, the psychologist, worries that with demand exceeding supply, agencies might overlook vulnerability in a potential surrogate to move the process along. “They are guidelines,” she said. “Not everyone follows them.”
Riddle said that her clinical work with surrogates has fed into her research. She would meet with gestational carriers, but wondered about the effects on their children. Her research, Riddle said, is “a tiny attempt, on my part, to really elevate the ethical challenges of this practice so that we can all work to protect vulnerable people.” Some of her studies have probed the families of surrogates and found that a small number of children whose mothers served as surrogates felt anxiety or sadness. But the research examined just a few families: One study involved just seven surrogates and 13 children; the 38 percent of kids with a negative response to their mother’s subsequent surrogate pregnancy was made up of five children.
Legal and medical experts alike would like to see further research and regulation because, in their absence, the number of people embarking on surrogacy continues to rise. McColgan echoed the point. “I would say definitely a hundred percent: A lot more needs to be done,” he said, adding that, for him, the end goal is universal regulation. (While some scholars agree, this would be hard to achieve.) “There needs to be more studies in the U.S. and even within states in the U.S., because, like I said, there’s so much variability,” McColgan said.
Navis, the Portland dentist, has no regrets about her surrogacy even though the birth was so complicated that doctors thought she might need not one blood transfusion but two. She did it because she wanted to, she said. And if a woman likes being pregnant, the choice is up to her, she suggested. Even the day after the traumatic birth, “I was just like, that was a good experience.”
And Spaans, the Washington mom who is carrying her friend’s child, said that she had some depression during her first trimester, which was hard, but now loves the process. She sometimes feels anxious when she sees people seeking surrogates on Reddit threads because they haven’t done their research and there are so many ways for situations to go awry. But for her, the experience is different. Her mother-in-law asked how she could give up the baby, who recently started to kick. Spaans said she doesn’t see it that way: “When I feel her, I’m like, this is so cool. There’s a baby that I get to give away and make somebody’s family whole.”