The tiny swimmers appear to transmit signals that "persuade" the female body to have a baby.
The following article was originally published on our sister site, Freethink.
New research suggests that sperm play a bigger role in pregnancy than previously believed, not only fertilizing the egg, but also "persuading" the female body to accept it.
Revisiting sex ed: Human reproduction typically starts with sperm traveling via seminal fluid to an egg and fertilizing it. That creates a zygote, which can then attach to the wall of the uterus and begin the process of developing into a baby.
Implantation isn't a given, though. The woman's immune system may reject the fertilized egg as something "foreign" and prevent her from becoming pregnant.
Persuasive swimmers: Past research has shown that seminal fluid contains proteins that dampen this immune response, encouraging the woman's body to accept the zygote and the pregnancy.
Now, researchers at the University of Adelaide have discovered that sperm send their own signals designed to persuade the woman's body.
"This overturns our current understanding of what sperm are capable of," project leader Sarah Robertson said in a press release. "They are not just carriers of genetic material, but also agents for convincing the female to invest reproductive resources with that male."
The study: For a new study, female mice were mated with males who produced sperm and males who'd been vasectomized (meaning they produced seminal fluid without sperm).
Based on changes in the expression of different genes in the females' uteruses, the researchers determined that the sperm-producing mice prompted a stronger immune tolerance in their mates than the vasectomized rodents.
By introducing male sperm to female cells in the lab, the researchers were able to confirm that the sperm was directly responsible for the changes.
Why it matters: Infertility is a common issue, affecting tens of millions of couples across the globe, and problems such as recurrent miscarriage, preeclampsia, and stillbirth have all been linked to the female immune response during reproduction.
Now that we know that sperm can affect that immune response, researchers may be able to identify new ways to treat infertility — potentially helping some couples conceive and give birth to healthy babies.
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New research from the University of Granada found that stress could help determine sex.
- A new study found that women with elevated stress before, during, and after conception are twice as likely to deliver a girl.
- One factor could be that sperm carrying an X chromosome are better equipped to reach the egg under adverse conditions.
- Another factor could be miscarriage of male fetuses during times of stress.
Stress in the modern world is generally viewed as a hindrance to a healthy life.
Indeed, excess stress is associated with numerous problems, including cardiovascular disease, high blood pressure, insomnia, depression, obesity, and other conditions. While the physiological mechanisms associated with stress can be beneficial, as Kelly McGonigal points out in The Upside of Stress, the modern wellness industry is built on the foundation of stress relief.
The effects of stress on pregnant mothers is another longstanding area of research. For example, what potential negative effects do elevated levels of cortisol, epinephrine, and norepinephrine have on fetal development?
A new study, published in the Journal of Developmental Origins of Health and Disease, investigated a very specific aspect of stress on fetuses: does it affect sex? Their findings reveal that women with elevated stress are twice as likely to give birth to a girl.
For this research, the University of Granada scientists recorded the stress levels of 108 women before, during, and after conception. By testing cortisol concentration in their hair and subjecting the women to a variety of psychological tests, the researchers discovered that stress indeed influences sex. Specifically, stress made women twice as likely to deliver a baby girl.
The team points out that their research is consistent with other research that used saliva to show that stress resulted in a decreased likelihood of delivering a boy.
Maria Isabel Peralta RamírezPhoto courtesy of University of Granada
Lead author María Isabel Peralta Ramírez, a researcher at the UGR's Department of Personality, Evaluation and Psychological Treatment, says that prior research focused on stress levels leading up to and after birth. She was interested in stress's impact leading up to conception. She says:
"Specifically, our research group has shown in numerous publications how psychological stress in the mother generates a greater number of psychopathological symptoms during pregnancy: postpartum depression, a greater likelihood of assisted delivery, an increase in the time taken for lactation to commence (lactogenesis), or inferior neurodevelopment of the baby six months after birth."
While no conclusive evidence has been rendered, the research team believes that activation of the mother's endogenous stress system during conception sets the concentration of sex hormones that will be carried throughout development. As the team writes, "there is evidence that testosterone functions as a mechanism when determining the baby's sex, since the greater the prenatal stress levels, the higher the levels of female testosterone." Levels of paternal stress were not factored into this research.
Previous studies show that sperm carrying an X chromosome are better equipped to reach the egg under adverse conditions than sperm carrying the Y chromosome. Y fetuses also mature slowly and are more likely to produce complications than X fetuses. Peralta also noted that there might be more aborted male fetuses during times of early maternal stress, which would favor more girls being born under such circumstances.
In the future, Peralta and her team say an investigation into aborted fetuses should be undertaken. Right now, the research was limited to a small sample size that did not factor in a number of elements. Still, the team concludes, "the research presented here is pioneering to the extent that it links prenatal stress to the sex of newborns."
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A large new study puts caffeine-drinking moms on alert.
- A study finds that the brains of children born to mothers who consumed coffee during pregnancy are different.
- Neuroregulating caffeine easily crosses the placental barrier.
- The observed differences may be associated with behavioral issues.
As one human body gives birth to another, so many things have to, and usually do, go right. It's known that substances a mother ingests can influence the success of fetal development. Modern mothers are careful regarding the consumption of alcohol, associated with a wide array of problems during fetal development and later in life.
Researchers have also investigated the impact of coffee consumption during pregnancy. It's known that caffeine easily traverses the placenta and that a fetus lacks the enzymes necessary to break down this known neuroregulatory compound. Studies have found that the coffee's caffeine can result in lower birth weights when too much of the beverage is consumed.
Now a substantive study from researchers at the Del Monte Institute for Neuroscience at the University of Rochester states definitively that coffee during pregnancy can change important fetal brain pathways that may lead to behavioral issues later in life.
What's too much coffee? First author Zachary Christensen says, "Current clinical guidelines already suggest limiting caffeine intake during pregnancy—no more than two normal cups of coffee a day. In the long term, we hope to develop better guidance for mothers, but in the meantime, they should ask their doctor as concerns arise."
This guidance may change as a result of this study, notes principal investigator John Foxe, who says, "I suppose the outcome of this study will be a recommendation that any caffeine during pregnancy is probably not such a good idea."
The study is published in the journal Neuropharmacology.
A large study of nine- and ten-year-old brains
Credit: myboys.me/Adobe Stock
For the study, researchers analyzed brain scans of 9,000 nine and ten-year-olds. Based on their mothers' recollections of their coffee consumption during pregnancy, the researchers found that children of coffee drinkers had clear changes in the manner in which white brain matter tracks were organized. These are the pathways that interconnect brain regions.
According to Foxe, "These are sort of small effects, and it's not causing horrendous psychiatric conditions, but it is causing minimal but noticeable behavioral issues that should make us consider long-term effects of caffeine intake during pregnancy."
Christensen says that what makes this finding noteworthy is that "we have a biological pathway that looks different when you consume caffeine through pregnancy."
Of children with such pathway differences, Christensen says, "Previous studies have shown that children perform differently on IQ tests, or they have different psychopathology, but that could also be related to demographics, so it's hard to parse that out until you have something like a biomarker. This gives us a place to start future research to try to learn exactly when the change is occurring in the brain."
The study doesn't claim to have determined exactly when during development these changes occur, or if caffeine has more of an effect during one trimester or another.
Foxe cautions, "It is important to point out this is a retrospective study. We are relying on mothers to remember how much caffeine they took in while they were pregnant."
So as if being pregnant wasn't difficult enough, it sounds like the most conservative and safe course of action for expectant mothers is to forgo those revitalizing cups of Joe and switch to decaf or some other un-caffeinated form of liquid comfort. We apologize on behalf of science.
"Such studies will lead to a better understanding of brain development in both autistic and typical individuals."
- Autism spectrum disorder (ASD) is a neurodevelopmental condition that can cause significant social, communication, and behavioral challenges.
- Although a diagnosis of autism can typically be made around the age of 2, the average age for diagnosis in the United States is after 4 years old.
- A new study shows that the atypical development of autism in human brain cells starts at the very earliest stages of brain organization, which can happen as early as the third week of pregnancy.
Autism spectrum disorder (ASD) is a neurodevelopmental condition that can cause significant social, communication, and behavioral challenges. According to the CDC, a diagnosis of autism now includes several conditions that used to be diagnosed separately (autistic disorder, pervasive developmental disorder, and Asberger syndrome). These conditions are now wrapped into the ASD diagnosis.
The American Academy of Pediatrics recommends that all children be screened for autism at 18 months and at 24 months, yet only about half of primary care practitioners in the United States screen for autism. Although a diagnosis of autism can typically be made around the age of 2, the average age for diagnosis in the United States is more than 4 years old.
Nerve cells in the autistic brain differ before birth, new research finds
The study was performed by scientists at King's College London and Cambridge University.
The study used induced pluripotent stem cells to recreate the development of each sample in the womb.
The researchers isolated hair samples from nine autistic people and six typical people. By treating the cells with an array of growth factors, the scientists were able to drive the hair cells to become nerve cells (or neurons), much like those found in either the cortex or the midbrain region.
These induced pluripotent stem cells (referred to as IPSCs) retain the genetic identity of the person from which they came, and the cells restart their development as it would have happened in the womb. This provides a look into that person's brain development.
At various stages, the researchers examined the developing cells' appearance and sequenced their RNA to see which genes the cells were expressing. On day 9 of the study, developing neurons from typical people formed "neural rosettes" (an intricate, dandelion-like shape indicative of typically developing neurons). Cells from autistic people formed smaller rosettes (or did not form any rosettes at all), and key developmental genes were expressed at lower levels.
Days 21 and 35 of the study showed cells from typical and autistic people differed significantly in a number of ways, proving that the makeup of neurons in the cortex differs in the autistic and typically developing brains.
John Krystal, Ph.D., Editor-in-Chief of Biological Psychiatry, explains: "The emergence of differences associated with autism in these nerve cells shows that these differences arise very early in life."
Along with the variations, there were some things that proved similar.
Additionally, cells directed to develop as midbrain neurons (a brain region that's not implicated in autism dysfunction) showed only negligible differences between typical and autistic individuals. The similarities are just as important as the differences, as they mark how the autistic brain and typical brain develop uniquely from the earliest stages of growth.
"The use of iPSCs allows us to examine more precisely the differences in cell fates and gene pathways that occur in neural cells from autistic and typical individuals. These findings will hopefully contribute to our understanding of why there is such diversity in brain development," said Dr. Dr. Deepak Srivastava, who supervised the study.
The intention of this study is not to find ways to "cure" autism, but to better understand the key genetic components that contribute to it.
Simon Baron-Cohen, Ph.D., Director of the Autism Research Centre at Cambridge and the study's co-lead, added that "some people may be worried that basic research into differences in the autistic and typical brain prenatally may be intended to 'prevent,' 'eradicate,' or 'cure' autism. This is not our motivation, and we are outspoken in our values in standing up against eugenics and in valuing neurodiversity. Such studies will lead to a better understanding of brain development in both autistic and typical individuals."
The CDC's latest youth risk survey houses some scary numbers but shows that evidence-based sex education is working.
It's a well-worn truism that teenagers take risks—whether its drugs, drinking, shoplifting, or drag racing down the L.A. River against their 30-year-old gang rivals. On the flip side of that truism, parents worry endlessly that those risks will result in life-altering consequences. And there's perhaps no risk more fraught with worry than when and how teenagers will become sexually active.
Boys and girls begin puberty early in their teens, an age established during our 200,000-year evolutionary history. Yet, this time frame is horribly mismatched with modern cultures and societies. Today's teenagers reach psychosocial maturity much later and build life plans centered on long-term education and career goals. Thankfully, in the 20th century we developed safe, effective contraceptives and prophylactics, granting us a chance to find harmony between our modern realities and evolutionary drives.
But do teenagers engage in safe sex, or are they taking unnecessary risks during their first sexual escapades? That's the question the CDC hopes to answer with its Youth Risk Behavior Surveillance System. This biennial, nationwide survey aims to monitor health-related risk behaviors among high school students. And when it comes to sex, the survey's findings are both promising and a tad terrifying.
Are the kids alright?
A graph showing the prevalence of condom and primary contraceptive use among high school students during their last sex act.
First some good news: About 90 percent of sexually active high school students report using either a condom or other primary contraceptive method. Condoms were the most used form of contraceptive, with about half of that cohort claiming to have used one during their previous act of intercourse. Sexually active students made up about a quarter of all respondents, meaning more adolescents are choosing to wait until at least their late teens to have sex.
Looking at long-term data, today's teenagers make better decisions than their '90s peers. When the survey began in 1991, more than 50 percent of respondents claimed to have engaged in sex at least once. Of those, 16 percent said they used no method of birth control while 10 percent said they had sex before the age of thirteen. In 2019, 38 percent of respondents claimed to have had sex at least once. Of those, only 12 said they used no birth control while 3 percent said they had sex before thirteen.
Overall, the CDC reports adolescence to be a healthy stage in people's lives.
Now for some bad news: Condom use among sexually active teens has decreased. While 2019's 54 percent represents an uptick from the 1990's, it is a headlong drop from 2003's high of 63 percent. Granted, condom use may be underestimated due to survey limitations. For example, respondents could only select one birth control method for their latest sexual act. This means they could have considered another method as their primary birth control while leaving condom use unaccounted for. Even so, 2019's tally still suggests too many teenagers take unnecessary risks with pregnancy and STD transmission.
Other troubling figures also emerged. About a fifth of sexually active teens report using either no contraception or using a highly ineffective method, such as withdrawal. Only 9 percent report pairing an effective birth control with a condom. That figure may also be underestimated as half of the respondents were teenage boys, who—let's face it—may not have the most reliable grasp on female contraception use.
Teenagers and people in their early 20s represent about half of the 20 million new cases of STDs each year in the U.S. So, while 90 percent of sexually active teenagers may be protecting themselves from unintended pregnancies, many still risk their health in other ways. This is why experts recommend teens pair a condom with an effective birth control. It provides extra protection from unintended pregnancy while adding a prophylactic element to hinder the spread of STDs.
Having the talk
What can be done to bolster positive trends and reverse negative ones? Continue advancing sex education and outreach programs. In the survey, the CDC notes the proven effectiveness of risk reduction education—that is, not fearmongering but comprehensive, evidence-based teaching.
Unfortunately for adults hoping to avoid awkward conversations with banana stand-ins, this means doing away with abstinence-only programs. A review of the scientific literature found that these programs contain "scientifically inaccurate information, distort[ed] data on topics such as condom efficacy, and [promotion] of gender stereotypes." It concluded that abstinence-only programs put teens at greater risk of unintended pregnancies and STDs. With the gap between sexual maturity and marriage ever-widening, such programs, no matter how well-intended, are simply unrealistic.
As Laura Grubb, author of the American Academy of Pediatrics guidelines on adolescent barrier protection, told CNN:
It does not have to be a controversial position. There is no evidence that providing contraception to adolescents makes them more sexually active or promotes risky behavior. […] In fact, comprehensive evidence-based sexuality education results in adolescents delaying sexual behavior, using contraception at first intercourse, and having less sexual partners at a young age."
The CDC also recommends strong partnerships between communities and clinics. Teens should have access to well-trained care providers to provide the information and services they need.
Sex comes with risks, and it is impossible to reduce a teen's risk factor to zero. That's not necessarily a bad thing. Risk-taking is how teenagers develop their independence and form the identities that will carry over into their adult lives. It helps them experience qualities of the world that were hidden to them as children. But without comprehensive education, the consequences of those risks may stay hidden until it's too late. And without access to proper outreach and resources, they may not have the means to mitigate those risks.
As for drugs, drinking, shoplifting, and drag racing down the L.A. river for pinks, those are topics for other surveys and articles.