While researching preeclampsia in Guadeloupe in the early 1990s, Pierre-Yves Robillard came to a realization that shook the foundations of his field.Preeclampsia, a contributing pregnancy complication Approximately 500,000 fetal deaths and 70,000 maternal deaths Every year, this condition is considered the most common among new mothers around the world, as the mother’s body intensifies its inappropriate attacks on her first child. But Robillard, now a neonatologist and epidemiologist at Réunion University Hospital Center on Réunion Island in the Indian Ocean, I kept watching the situation change rapidly. During the second, third, or fourth pregnancies, this pattern has also been documented in several other studies, but is not yet fully explained. Then Robillard realized something else. “These women changed her father,” he told me. He finally deduced that the trigger for these cases of preeclampsia was not newness. pregnancy. It was the newness of the father’s genetic material that the mother probably hadn’t had enough exposure to before.
Robillard’s ideas were unconventional because they not only challenged the established theories of the time, but also implied specific evolutionary outcomes.Preeclampsia appears to be limited (or almost exclusive) For humans, it may have arisen as a byproduct of a particularly aggressive way in which the fetus preys on the mother’s body for resources. So Robillard and his colleagues hypothesized that perhaps the danger it posed pressured humans to develop a strange trait: they were significantly less efficient at procreating. Perhaps if human fertility were not so high, we would need to have a lot of sex. Most likely, having sex many times will expose her mother to her partner’s semen, instilling in her the molecular structure of her future offspring.If pre-eclampsia is a type of immune overreactionThen, unprotected sex is probably the world’s most unconventional allergic reaction.
At least, that’s what Robillard and his colleagues claim, an idea that is “a little controversial and a little awkward,” said Inkeli Lokki, an immunologist and reproductive biologist at the University of Helsinki. She remembers a senior researcher in the field once stating the conclusion of a hypothesis: “Choose a partner early and put it into practice.”
Foreign genetic material aside, there are good reasons for mothers to be wary of their fetuses. Pregnancy is intergenerational struggle In this case, the fetus tries to plunder all the nutrients it can from the mother’s tissues, while the mother tries to save some of her own resources.
In most mammals, the two easily enter into a permanent stalemate. But among humans, the fetus gets a “head start,” said Amy Boddy, an evolutionary biologist at the University of California, Santa Barbara.Is it due to the extreme nutritional demands of the energy-consuming brain, or is it simply constraints of How did the primate lineage evolve?no other developing mammals invade as active as a human fetus: throughA wave of invasionOur placental cells burrow very deep into the endometrium, breaking through the muscle layer, where they widen, dissolve, and rewire entire blood vessels until they spread and relax. In the process, tissues are liquefied and cells are forced apart, all while “huge amounts of blood are pumped to the placenta,” says Julian Rutherford, a biological anthropologist at the University of Arizona School of Nursing. Told.
The fetus will still grow in these conditions, but it will demand so much from the mother’s body that it will likely rebel. Therefore, preeclampsia is probably a manifestation of the human maternal condition, at least if it occurs before 34 weeks of gestation. Defenses respond wisely to invasions and then go into overdrive. When researchers examine tissue samples from patients with early-onset preeclampsia, they tend to find that the placenta is well-prevented from entering the uterus, said Haley Ragsdale, a biological anthropologist at Northwestern University. It is said that there is. The fetus, at risk of starvation, tries to suck more juice from the mother by increasing the mother’s blood pressure, a characteristic symptom of preeclampsia. (High blood pressure that occurs during the last few weeks of pregnancy can be a sign of late-onset preeclampsia, but researchers generally think the causes are different.)
Ofer Erez, an obstetrician-gynecologist at Soroka University Medical Center in Israel, told me why exactly the placental invasion flag in early-onset cases remains controversial. One possibility, Robillard and colleagues argue, is that the mother’s immune system, unaccustomed to her partner’s particular mix of molecules, encodes the fetus as foreign and dispatches a defense fleet to thwart the threat. It is something. If this is indeed the case, a logical workaround would be to get her body used to these foreign objects and nip her overreactions in the bud.
Semen may be effective: Packed with paternal substances, it is introduced into the vaginal canal, where a large number of immune cells and molecules roam.Also includes signal transduction molecules It can weaken the mother’s immune system. Repeated innocuous exposures send a clear message. i am safesays Gustav Dekker, head of obstetrics and gynecology at Australia’s Adelaide Northern Regional Health Network and a longtime collaborator with Robillard.
Over the past 30 years, Decker, Robillard, and their colleagues have amassed a wealth of information. evidence To support that idea.In some populations, the risk of early-onset preeclampsia appears to be higher among couples pregnant First time; it’s expensive people using it Donor sperm and eggs.There seems to be a risk lower between couples Having frequent penetrative or oral sex before they get pregnant— at least, some studies suggest, if you don’t use a condom.There is even evidence that repeated exposure to semen Female mice can be made more resistant to cells taken from their spouses.
From an evolutionary perspective, this theory goes even further. If it is important to inculcate the mother’s immune system with semen, this would create a “strong selection pressure” for humans. series of actions Bernard Crespi, an evolutionary biologist at Canada’s Simon Fraser University who collaborates with Robillard, says the idea is to increase exposure. Our bodies’ combative approach to placentation may explain our semi-monogamous nature, relatively low fertility among mammals, and relatively large testes that can provide an abundant supply of sperm. may be helpful. It may even influence the unusual ways in which the human female body hides its reproductive potential. Unlike other mammals, we do not have regular, overt heat cycles or visible signals of ovulation. Both of these characteristics encourage more frequent sex for reproductive purposes.When repeat coupling is just a type of about usperhaps that’s because they make our pregnancies safer.
The paternal immunity hypothesis is not the only possible explanation for early-onset preeclampsia, and for some researchers it is far from the most likely hypothesis. fathers May play another role in symptoms. Laura Schultz, a women’s health researcher at the University of Missouri School of Medicine, says there is some evidence to suggest that certain men pass on DNA that makes their offspring more likely to implant slightly differently in the womb. It pointed out. And immunocompatibility may also be important, Carlos Galaviz Hernández, a geneticist at Mexico’s CIIDIR Unidad Durango, told me. Matches that may make mothers more tolerant of some partners, just as certain molecular signatures can make organ transplants more successful. In some cases, mother’s DNA may be the dominant force. For example, certain women think: likely to be genetic You can develop symptoms regardless of who you partner with.
Jimmy Espinoza, a maternal-fetal medicine specialist at UTHealth Houston’s McGovern Medical School, also pointed out to me that the ideas Robillard has been championing have their own scientific problems. Especially in recent years, other research teams have discovered that: evidence That seems like a direct contradiction to that, Several Case, find That may be true for some people reduce their chance If you switch to a different partner for your next child, you may have pre-eclampsia. (Decker and Robillard claim Some of these studies were found to have problems, including potential for misdiagnosis and insufficient differentiation between early-onset and late-onset preeclampsia. )
All of these thoughts may have some truth to them. preeclampsialike cancer“It’s an umbrella term for a variety of disease pathways that have similar end-stage symptoms,” said Andrea Edlow, a maternal-fetal medicine specialist at Massachusetts General Hospital. And despite evidence to the contrary, “I still support that hypothesis,” Decker told me. In his opinion, “no one has come up with anything better.”
Even if the semen hypothesis turns out to be correct, it’s hard to know what to do do With that information. Breakthroughs are desperately needed. Although preeclampsia has been recorded for thousands of years, diagnosis, treatment, and prevention methods are lacking. Perhaps a better understanding of paternal exposures will one day lead to preconception vaccines or targeted immunotherapies for people considered at high risk. But today, the most practical takeaway from this idea is very limited. In Robillard’s ideal world, clinicians would recommend at least six months of sexual cohabitation or at least 100 sexual encounters before pregnancy. Pregnant people will also regularly disclose their sexual history with their partners to their doctors. change in the partner listed in the medical record. Unsurprisingly, pitching some of these ideas to colleagues “was an uphill battle,” Decker said.
Edlow, for example, generally supports the idea of paternal tolerance. But “that’s not something I tell my patients,” she told me. Sarah Kilpatrick, director of obstetrics and gynecology at Cedars-Sinai Hospital in Los Angeles, feels similarly. There simply isn’t enough evidence to make recommendations, and designing large clinical trials to rigorously test these ideas is difficult, especially for a disease that carries such significant risks. It’s difficult, she told me.
Additionally, pre-pregnancy injunctions Let’s have more sex Reducing the risk of preeclampsia is actually only applicable to a very limited number of people. It assumes heterosexuality. It means monogamy. Even the amount of sex that Robillard advocates can be a challenge for some couples who meet that criteria. And heterosexual monogamous couples are not representative of the entire world of people trying to conceive. These include those pursuing single parenthood, those who conceive through intrauterine insemination or in vitro fertilization, those seeking donor sperm or embryos, and those who become pregnant quickly. Or perhaps unintentionally. And while some of these cohorts may have a slightly higher chance of pre-eclampsia, most broadly speaking, we can’t understand why person X gets it and why person Y doesn’t get it. I have no idea,” Kilpatrick told me. Furthermore, clinical strategies that appear to promote or even justify long-term sexual monogamy have placed medical professionals in a position to actively prescribe a very specific and limited vision of human sexuality. Rutherford, the biological anthropologist, told me.
Frankly, Edlow told me, “I don’t want to make this condition that affects pregnancy all about the male sperm.” There may still be other ways to induce tolerance or suppress the mother’s immune system. Pre-eclampsia may be an evolutionary twist that somehow our lineage has gotten caught up in. But to address or resolve it, people may not have to submit to the whims of evolutionary theory.
