Category: Obstetrics & Gynaecology

Categories : Cardiovascular Disease Obstetrics & GynaecologyTags :

The Risks of Various Menopausal Hormone Treatments Vary

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Photo by cottonbro studio:

Researchers have analysed the effects of seven different hormone treatments for menopausal symptoms, and the risk of blood clots, stroke and heart attack. The risks differ depending on the active substance and how the medicine is taken, according to the study findings which appear in the BMJ. In this world’s largest and most comprehensive study of currently prescribed hormonal substances, researchers analysed the risks for one million women aged 50–58.

“There is concern among women that menopausal hormone therapy increases the risk of cardiovascular disease. This concern is based on older studies conducted more than 20 years ago that only looked at one type of treatment. Since then, many new preparations have been introduced and our study shows that the previous conclusions do not apply to all types of treatments,” says Therese Johansson, postdoctoral researcher and lead author of the study, which was part of her thesis at Uppsala University.

To counteract the health effects of menopause, such as hot flashes and osteoporosis, women may be prescribed hormone replacement therapy which consists of hormones or hormone-like substances.

Treatment available since the 1970s

In Sweden alone, hundreds of thousands of women currently use hormone replacement therapy and this type of treatment has been available since the 1970s. At that time, there was only one type of hormone replacement therapy and when a major study in the 1990s showed that it increased the risk of cardiovascular disease, its use rapidly declined. Since then, new preparations have entered the market, and following this, the use of hormone replacement therapy in connection with menopause has increased significantly in recent years.

In the new study, the researchers looked at seven different types of currently used hormone replacement treatments, administered via tablets, hormone patches or hormone-releasing IUDs. The study is based on all prescriptions for hormone replacement therapy in Sweden from 2007 to 2020 and covers nearly one million women aged 50 to 58. The women were monitored for two years after starting hormone replacement therapy. The risk of blood clots and cardiovascular disease was compared between women who had and had not collected a prescription medicine for hormone replacement therapy.

Different therapies, different risks

The results show clearly that the risks of hormone replacement therapy vary depending on the type of treatment.

For example, the synthetic hormone tibolone, which mimics the effects of the body’s natural hormones, was linked to an increased risk of both heart attack and stroke, but not to an increased risk of blood clots. The risk of heart attack or stroke due to tibolone is estimated at one in a thousand women.

Combined preparations containing both oestrogen and progesterone instead increase the risk of blood clots, including deep vein thrombosis and pulmonary embolism. The researchers estimate that the risk of deep vein thrombosis resulting from this combined preparation is about 7000 women per year.

“It is important that both doctors and women are aware of the risks of menopausal hormone therapy and, in particular, that the existing drugs carry different risks of blood clots and cardiovascular disease. Tibolone in particular was associated with an increased risk of stroke and heart attack. Tibolone is used in Europe but is not approved in countries such as the United States. We hope that our study will lead to the drug being withdrawn from use here as well,” says Åsa Johansson, research group leader at Uppsala University and SciLifeLab, and the study’s senior author.

During the period of the study, 2007–2020, a roughly 50% increase hormone patch use was observed, and these preparations were not linked to the same higher risk. The increased use of safer alternatives, such as patches, is an important step forward in reducing the risk of cardiovascular disease among menopausal women.

Identify individual increased risk

“The next step in our research will be to develop strategies to identify which women are at increased risk of certain diseases in connection with using hormonal drugs. In this way, we can guide patients to the most appropriate medicine for each individual and drastically reduce the number of side effects,” Åsa Johansson says.

Source: Uppsala University

Categories : Obstetrics & GynaecologyTags :

Pregnancy Complications make Women Less Inclined to Have More Children

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Photo by Jonathan Borba on Unsplash

Women who suffer severe complications during their first pregnancy or delivery are less inclined to have more babies, according to a study published in JAMA by researchers at Karolinska Institutet. For Sweden, given its recent steady decline in birth rate, the researchers propose monitoring in antenatal care to address the problem.

“The clinical monitoring of these women is essential, and they need individualised advice on possible future pregnancies,” says the study’s first author Eleni Tsamantioti, doctoral student at the Department of Medicine in Solna, Karolinska Institutet.

Reduced fertility

Birth rates and fertility have both been in steady decline in Sweden over the past years. In this new population-based study, the researchers have studied the association between severe maternal morbidity in first-time mothers and the likelihood of their having a second baby. The study comprised over a million women in Sweden who had their first baby between 1999 and 2021.

“We found that the likelihood of having more children was much lower in women who had experienced severe complications during their first pregnancy, delivery or postnatal period,” says the study’s last author Neda Razaz, associate professor at the same department. “Such events can often have a physical and mental impact on women for a long time to come.”

All in all, 3.5% of the first-time mothers in the study suffered serious complications and were 12% less likely to have a second baby. Most impacted were women who had experienced cardiac complications, a ruptured uterus or severe mental health problems, who were 50% less likely to have another birth than women who had not experienced such complications.

Monitoring in antenatal care

Women who needed respiratory care or who suffered a cerebrovascular accident like stroke or intracranial haemorrhage were 40% less likely to have a second baby. Acute kidney failure, severe preeclampsia and blood clotting were also associated with a lower probability of a second pregnancy. The researchers also compared the women with any sisters they had to control for familial factors. 

“The reasons are hard to speculate on and may result from multiple factors, such as decreased desire for more children, trauma, infertility related to psychiatric medications, or lack of health counselling,” says Tsamantioti. “Proper support and monitoring by antenatal care staff is therefore essential for women who have suffered serious health problems during pregnancy or delivery.”

Source: Karolinska Institutet

Categories : Medical Industry Obstetrics & GynaecologyTags :

Bayer Issues Recall on YAZ Plus Contraceptive Pills

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Photos supplied by Bayer showing the affected blister (left) and the normal blister (right).

On November 21, Bayer (Pty) Ltd issued a medicine recall for a specific batch (WEW96J) of YAZ PLUS tablets. In a press release, they explain the reason for the recall: it has been discovered that the active and inactive tablets in this batch are swapped. This mix-up has resulted in some packs containing only four hormone tablets instead of the required 24, and 24 hormone-free tablets instead of four, compromising the product’s contraceptive efficacy.

The company advises that healthcare professionals, wholesalers, hospitals, retail pharmacy outlets, doctors, nurses, pharmacists, authorised prescribers, dispensers, and individual customers or patients in possession of the affected batch can return product to their healthcare facility from which it was dispensed, for credit.

Bayer urges that if you are in possession of YAZ PLUS tablets from the affected batch, to do the following:

  1. Stop Use Immediately: If you have been taking the tablets from a batch that is affected with the mix-
    up, stop taking them immediately and contact your healthcare professional. While only a limited number of packs from the respective batch is affected, as a precautionary measure, no tablets from these packs shall be used until you have consulted your Healthcare Practitioner, as they may potentially not provide the contraceptive protection you expect.
  2. Return the Product: Please return any affected packs to the pharmacy or retailer where you
    purchased them for a replacement or refund.
  3. Check Your Packs: If you have multiple packs of YAZ PLUS, please check each one of them, to
    ensure they are not from the affected batch.
  4. Consult Healthcare Provider: If you have consumed tablets from the affected batch, or if you have
    concerns about your contraceptive coverage, please consult your healthcare provider as soon as
    possible for advice.

In the press release, Bayer says that it “takes the safety and efficacy of its products seriously and is committed to ensuring that all YAZ PLUS tablets in the market meet the highest quality standards.” It further advises that the root cause for the mix-up of tablets in the packaging has been identified and corrective measures taken. Only this one batch – and no others – was affected.

“The company is working diligently with SAHPRA and healthcare providers to facilitate the recall process and minimise any inconvenience to our customers. We are dedicated to addressing this issue promptly and ensuring the continued health and safety of all our customers.”

Further Information and Support:
For more information about this recall, or if you have any questions or concerns, please contact Bayer +27
(0) 11 921 5000. Our team is available to provide the support and information you need.
Report a side effect: Patient Safety Reporting – Introduction
Report a product quality complaint for Pharmaceutical Products: afptc@bayer.com

Categories : Obstetrics & GynaecologyTags :

Short-term Menopausal Hormone Therapy has no Long-term Cognitive Impact

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Photo by Teona Swift on Unsplash

Women in early postmenopause taking short-term MHT had no cognitive effects a decade later

Short-term menopausal hormone therapy (MHT) did not have long-term cognitive effects when given to women in early postmenopause, according to a study published November 21st in the open-access journal PLOS Medicine by Carey Gleason from the University of Wisconsin-Madison, USA, and colleagues.

While MHT can offer relief from the challenging symptoms of menopause, many women and doctors are hesitant to start MHT due to safety concerns. Previous research has linked one form of hormone therapy to mild cognitive impairment and dementia in women older than 65 years of age, prompting research on the importance of age and timing of therapy on cognitive impairment. Other studies have suggested that transdermal oestrogen may have long-term cognitive benefits.

In the Kronos Early Estrogen Prevention Study (KEEPS), women in early postmenopause with good cardiovascular health were randomised to receive one of two types of MHT (oral or transdermal oestrogen) or placebo. At the end of four years, no cognitive benefit or harm was seen in those who received MHT compared to the placebo group. However, long-term cognitive effects of MHT are still understudied.

In this new follow-up study – the KEEPS Continuation Study – researchers revisited participants nearly ten years later to repeat a series of cognitive tests. Among 275 women, although MTH failed to protect against cognitive decline, short-term MHT also had no long-term negative cognitive impact.

These findings may offer reassurance to women considering MHT while adding to the growing body of research supporting the importance of timing for MHT. More research is needed to investigate whether these results are generalisable to women with higher cardiovascular risk.

The authors add, “For women in menopause and the health care providers caring for them, getting direct, clear and evidence-based information about menopausal hormone therapy is challenging. And they need data to guide their decisions.”

Provided by PLOS

Categories : General Interest Obstetrics & GynaecologyTags :

Researcher Discovers Ancient Egyptian Mugs Contained Hallucinogens

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(a) Drinking vessel in shape of Bes head; El-Fayūm Oasis, Egypt; Ptolemaic-Roman period (4th century BCE − 3rd century CE), (courtesy of the Tampa Museum of Art, Florida). (b) Bes mug from the Ghalioungui collection, 10.7 × 7.9 cm (Ghalioungui, G. Wagner 1974, Kaiser 2003, cat. no. 342). (c) Bes mug inv. no. 14.415 from the Allard Pierson Museum, 11.5 × 9.3 cm (courtesy of the Allard Pierson Museum, Amsterdam; photo by Stephan van der Linden). (d) Bes mug from El-Fayum, dimensions unknown (Kaufmann 1913; Kaiser 2003, cat. no. 343). Credit: Scientific Reports, 2024

The first-ever physical evidence of hallucinogens in an Egyptian mug has been found, validating written records and centuries-old myths of ancient Egyptian rituals and practices. Through advanced chemical analyses, University of South Florida professor Davide Tanasi examined one of the world’s few remaining Egyptian Bes mugs.

Such mugs, including the one donated to the Tampa Museum of Art in 1984, are decorated with the head of Bes, an ancient Egyptian god or guardian demon worshiped for protection, fertility, medicinal healing and magical purification. Published in Nature’s Scientific Reports, the study sheds light on an ancient Egyptian mystery: The secret of how Bes mugs were used about 2000 years ago. 

“There’s no research out there that has ever found what we found in this study,” Tanasi said. “For the first time, we were able to identify all the chemical signatures of the components of the liquid concoction contained in the Tampa Museum of Art’s Bes mug, including the plants used by Egyptians, all of which have psychotropic and medicinal properties.”

The presence of Bes mugs in different contexts over a long period of time made it extremely difficult to speculate on their contents or roles in ancient Egyptian culture.

“For a very long time now, Egyptologists have been speculating what mugs with the head of Bes could have been used for, and for what kind of beverage, like sacred water, milk, wine or beer,” said Branko van Oppen, curator of Greek and Roman art at the Tampa Museum of Art. “Experts did not know if these mugs were used in daily life, for religious purposes or in magic rituals.”

Several theories about the mugs and vases were formulated on myths, but few of them were ever tested to reveal their exact ingredients until the truth was extracted layer by layer.

Tanasi, who developed this study as part of the Mediterranean Diet Archaeology project promoted by the USF Institute for the Advanced Study of Culture and the Environment, collaborated with several USF researchers and partners in Italy at the University of Trieste and the University of Milan to perform chemical and DNA analyses. With a pulverised sample from scraping the inner walls of the vase, the team combined numerous analytical techniques for the first time to uncover what the mug last held.

The new tactic was successful and revealed the vase had a cocktail of psychedelic drugs, bodily fluids and alcohol – a combination that Tanasi believes was used in a magical ritual re-enacting an Egyptian myth, likely for fertility. The concoction was flavoured with honey, sesame seeds, pine nuts, liquorice and grapes, which were commonly used to make the beverage look like blood.

“This research teaches us about magic rituals in the Greco-Roman period in Egypt,” Van Oppen said. “Egyptologists believe that people visited the so-called Bes Chambers at Saqqara when they wished to confirm a successful pregnancy because pregnancies in the ancient world were fraught with dangers. So, this combination of ingredients may have been used in a dream-vision inducing magic ritual within the context of this dangerous period of childbirth.”

“Religion is one of the most fascinating and puzzling aspects of ancient civilizations,” Tanasi said. “With this study, we’ve found scientific proof that the Egyptian myths have some kind of truth and it helps us shed light on the poorly understood rituals that were likely carried out in the Bes Chambers in Saqqara, near the Great Pyramids at Giza.”

The Bes mug is on display now at the Tampa Museum of Art and can be viewed in the exhibition, “Prelude: An Introduction to the Permanent Collection.” View a 3D model of the Bes mug produced by the USF Institute for Digital Exploration.

Categories : Diet and Nutrition Obstetrics & GynaecologyTags :

Many not Getting Enough Nutrients in Their Pregnancy, Study Finds

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Source: Pixabay CC0

It’s generally estimated that around 10% of pregnant people struggle to meet their nutritional needs – but the real number could be far higher, according to new research in The Journal of Nutrition.

Over 90% of pregnant individuals are potentially failing to get enough iron, vitamin D, or vitamin E from the food they eat, while over one-third could be short of calcium, vitamin C, and vitamin A. Troublingly, almost two-thirds of pregnant people were also found to be getting insufficient dietary folate – a critical nutrient that helps prevent birth defects in the baby’s brain and spine.

“It’s important to remember that many pregnant people take prenatal vitamin supplements, which might help prevent nutritional deficiencies,” says lead author Dr Samantha Kleinberg, professor at Stevens Institute of Technology. “Nonetheless, this is a startling finding that suggests we need to be looking much more closely at whether pregnant individuals are getting the nutrients they need.”

Where most previous studies of nutrition during pregnancy relied on a few days of food diaries, or on simply asking people what they remembered eating, the Stevens team asked pregnant people to take before-and-after photos of everything they ate over two 14-day periods. Experts then reviewed the photos to assess the amount of food actually eaten and determine the nutrients consumed during each meal.

That’s a far more accurate approach, because people are notoriously bad at estimating portion size or accurately reporting what they’ve eaten, Dr Kleinberg explains. A photo-based approach is also much less laborious for pregnant people, making it easy to collect data over a period of weeks instead of just a few days.

“Most surveys only track diet over a day or two – but if you feel off one day and don’t eat much, or have a big celebratory meal over the weekend, that can skew the data,” Dr Kleinberg says. “By looking at a longer time period, and using photos to track diet and nutrition, we’re able to get a much richer and more precise picture of what people actually ate.”

The study found significant dietary variations between individuals, but also among the same individuals from one day to the next, suggesting that shorter studies and population-based reports might be failing to spot important nutritional deficits. “Some people eat really well, and others don’t – so if you just take an average, it looks like everything’s fine,” Dr Kleinberg explains. “This study suggests that in reality, an alarming number of pregnant people may not be getting the nutrients they need from their food.”

Using food photos also recorded the exact timing of meals and snacks, and to explore the way that patterns of eating behaviour correlated with total energy and nutrient intake. When pregnant people ate later in the day, the data shows, they were likely to consume significantly more total calories – potentially an important finding as researchers explore connections between eating behaviours and health problems such as gestational diabetes.

The current research didn’t directly study health outcomes, so it’s too early to say whether insufficient nutrition or excessive energy consumption is adversely impacting pregnant individuals or their babies. “We’ll be digging into that in future studies, and looking at possible connections with eating patterns and changes in glucose tolerance,” Dr Kleinberg says.

Source: Stevens Institute of Technology

Categories : Neurology Obstetrics & GynaecologyTags :

How Human Brain Functional Networks Emerge and Develop during the Birth Transition

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Shedding light on the growth trajectory of global functional neural networks before and after birth

Photo by Christian Bowen on Unsplash

Brain-imaging data collected from foetuses and infants has revealed a rapid surge in functional connectivity between brain regions on a global scale at birth, possibly reflecting neural processes that support the brain’s ability to adapt to the external world, according to a study published November 19th, in the open-access journal PLOS Biology led by Lanxin Ji and Moriah Thomason from the New York University School of Medicine, USA.

Understanding the sequence and timing of brain functional network development at the beginning of human life is critical. Yet many questions remain regarding how human brain functional networks emerge and develop during the birth transition. To fill this knowledge gap, Thomason and colleagues leveraged a large functional magnetic resonance imaging dataset to model developmental trajectories of brain functional networks spanning 25 to 55 weeks of post-conceptual gestational age. The final sample included 126 foetal scans and 58 infant scans from 140 subjects.

The researchers observed distinct growth patterns in different regions, showing that neural changes accompanying the birth transition are not uniform across the brain. Some areas exhibited minimal changes in resting-state functional connectivity (RSFC) – correlations between blood oxygen level-dependent signals between brain regions when no explicit task is being performed. But other areas showed dramatic changes in RSFC at birth. The subcortical network, sensorimotor network, and superior frontal network stand out as regions that undergo rapid reorganisation during this developmental stage.

Additional analysis highlighted the subcortical network as the only region that exhibited a significant increase in communication efficiency within neighbouring nodes. The subcortical network represents a central hub, relaying nearly all incoming and outgoing information to and from the cortex and mediating communication between cortical areas. On the other hand, there was a gradual increase in global efficiency in sensorimotor and parietal-frontal regions throughout the foetal to neonatal period, possibly reflecting the establishment or strengthening of connections as well as the elimination of redundant connections.

According to the authors, this work unveils fundamental aspects of early brain development and lays the foundation for future research on the influence of environmental factors on this process. In particular, further studies could reveal how factors such as sex, prematurity, and prenatal adversity interact with the timing and growth patterns of children’s brain network development.

The authors add, “This study for the first time documents the significant change of brain functional networks over the birth transition. We observe that growth patterns are regionally specific, with some areas of the functional connectome showing minimal changes, while others exhibit a dramatic increase at birth.”

Provided by PLOS

Categories : Mental Health Obstetrics & GynaecologyTags :

Antiseizure Drugs during Pregnancy may Affect Neurodevelopment

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Photo by SHVETS production

Children whose mothers have taken antiseizure drugs during pregnancy are more likely than others to receive a neuropsychiatric diagnosis. This is according to a comprehensive study by researchers at Karolinska Institutet and elsewhere, published in Nature Communications. However, the researchers emphasise that the absolute risk is low.

Antiseizure drugs are used to treat epilepsy and to stabilise mood in certain psychiatric conditions. However, some of these drugs, such as valproate, are known to affect the foetus if used during pregnancy. 

The current study included data from over three million children in the UK and Sweden, 17 495 of whom had been exposed to antiseizure drugs during pregnancy. 

As expected, children exposed to valproate were more likely to be diagnosed with autism, intellectual disability or ADHD compared to children not exposed to antiseizure drugs. Children exposed to topiramate had a 2.5-fold increased risk of intellectual disability, while those exposed to carbamazepine had a 25 per cent increased risk of being diagnosed with autism and a 30 per cent increased risk of intellectual disability. 

No increased risk with lamotrigine 

However, the researchers found no evidence that taking the antiseizure drug lamotrigine during pregnancy increases the risk of neuropsychiatric diagnoses in the child. 

“Our findings suggest that while certain medications may pose some risk, lamotrigine may be a less risky option, but active monitoring of any antiseizure medication is critical to ensure safety and effectiveness, particularly during pregnancy,” says Brian K. Lee, Professor at Drexel University Dornsife School of Public Health, USA, and affiliated researcher at the Department of Global Public Health, Karolinska Institutet, Sweden. 

The researchers emphasise that the absolute risk of the child receiving a neuropsychiatric diagnosis is low and that there may also be risks associated with not taking antiseizure medication during pregnancy. 

“If you’re pregnant or trying to become pregnant, and taking one of these medications, it may be worth talking with your physician to make sure you’re taking the best medicine for your needs, while minimising risk to future children,” says Viktor H. Ahlqvist, researcher at the Institute of Environmental Medicine, Karolinska Institutet, and joint first author with Paul Madley-Dowd at the University of Bristol, UK. 

The results support previous findings from smaller studies that found links between antiseizure drugs during pregnancy and the risk of neuropsychiatric diagnoses in the child. One difference is that the new study found no statistically significant association between topiramate or levetiracetam and ADHD in the child. 

Source: Karolinska Institutet

Categories : Obstetrics & GynaecologyTags :

Having the Choice of Birth Position is Key in Satisfaction of Expectant Mothers

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Photo by Duda Oliveira

Whether supine, all-fours position, sitting upright or squatting – women adopt different birthing positions during childbirth. But until now, how the final birthing position affects the satisfaction of the woman giving birth had not been known. Researchers in Germany investigated the relationship. In particular, they also took into account whether the choice of birthing position was voluntary. The results, which appear in Archives of Gynecology and Obstetrics, showed that having the choice counted the most for mothers’ satisfaction.

Around three quarters of those surveyed were lying during the birth and were particularly dissatisfied if they felt that they had not made this choice themselves. But if the expectant mothers had chosen the supine or lateral supine position themselves, the position actually tended to make them more satisfied.

For a long time, the supine position was the most common birth position in Western countries, giving obstetricians unhindered access to the woman and child.  In various cultures, however, upright birthing positions, such as sitting or squatting, are also widespread. Which position is best for expectant mothers and the unborn child is controversial in the literature.

“Until today, international guidelines usually only recommend that women should adopt their preferred birthing position,” explains Prof Dr Nadine Scholten, professor in psychosomatic and psycho-oncological health services research at the University of Bonn. With regard to birthing positions, the German guideline also states that women should adopt the position that seems most comfortable to them. However, they should also be encouraged to adopt an upright position in the final phase of birth.

“In reality, whether they ultimately lie, sit or squat depends on the wishes of the expectant mothers themselves, but also on the suggestions of the midwives, obstetricians and sometimes necessary medical measures,” explains Prof Dr Brigitte Strizek, Director of the Clinic for Obstetrics and Prenatal Medicine at the University Hospital Bonn (UKB).

Focus on women’s satisfaction

A team led by Prof Scholten, who carried out the study at the Institute for Medical Sociology, Health Services Research and Rehabilitation Research (IMVR) at the University of Cologne and the UKB, wanted to find out which birthing position women were most satisfied with afterwards. Almost 800 mothers were asked about their final birthing position and how satisfied they were with the birth overall using an anonymous questionnaire. All of the data analysed here was from women who had given birth vaginally in a hospital without the use of a vacuum extraction or forceps, and who had given birth eight to twelve months previously at the time of the survey. In their study, the researchers also asked about the satisfaction of the mothers – depending on whether the birth position was freely chosen or not. The reasons for not choosing a free position were also asked.

It was found that over three quarters of mothers gave birth to their child lying on their side or on their back. Of these women, up to 40% stated that they had not chosen the birth position voluntarily. “The most common reason given by respondents was instructions from medical staff,” explains Prof Scholten, first and corresponding author. The most common position assigned by obstetricians was the supine position. It was striking that women were more satisfied with their birth if they were allowed to choose the position voluntarily – especially if they chose the supine position themselves. Women who were not free to choose their birthing position were particularly dissatisfied if the medical staff specified this and not the CTG to record the heart rate of the unborn child and labour activity or the epidural, the anaesthetic to relieve pain, prevented the desired position.

Self-determination not always given in the delivery room

“The number of women who did not choose the birth position themselves is particularly striking, as is the associated lower level of satisfaction with the birth,” summarises co-author Prof Strizek. However, the team cannot confirm whether an increased voluntary choice of birth position in the future would result in fewer women giving birth in the supine position. “In order to increase women’s subjective satisfaction with their birth experience, they should be given the opportunity to adopt their preferred position,” appeals lead author Prof Scholten. “The first step is to increase the awareness of medical staff and empower women to understand and better communicate their preferences.”

Prof Strizek adds: “If a certain position would be advantageous for the woman giving birth from a medical point of view, we as obstetric teams need to explain this better to the women so that they rarely have the feeling that they have not determined the birth position themselves.”

Source: Universitatsklinikum Bonn

Categories : Gender Obstetrics & GynaecologyTags :

Boy or Girl? This Genetic Mutation Increases Odds of Having a Daughter

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Source: Pixabay CC0

Each year, roughly the same numbers of boys and girls are born. But in individual families, some couples have four or more daughters and no sons, and some have all male children and no female children, points out University of Michigan evolutionary geneticist Jianzhi Zhang. This has led some scientists to question whether this skewed sex ratio is a result of the genes of the parents.

Now, Zhang and U-M doctoral student Siliang Song have detected a human genetic variant that influences the sex ratio of children. Additionally, they found that many hidden genetic variants of sex ratio may exist in human populations. Their results are published in the Proceedings of the Royal Society B: Biological Sciences.

“Scientists have been pondering and researching a genetic basis for sex ratio for decades, yet no unambiguous evidence for a genetic variation that alters the human sex ratio from an approximately 50:50 ratio has been found,” said Zhang, professor of ecology and evolutionary biology.

Zhang says this has led some scientists to think that the human sex ratio is not subject to mutation.

“But this scenario seems unlikely, because almost all human characteristics are subject to mutation and genetic variation,” he said. “Instead, we think genetic variation of sex ratio is too difficult to detect because sex ratio is not measured precisely.”

That is, each person typically has a very small number of children, which can lead to large errors in the estimation of the true sex ratio of a person’s children. For example, if a person only has one child, the estimated sex ratio would be either zero (if it’s a girl) or 1 (if it’s a boy) even if the true sex ratio is 0.5.

To detect genetic influence on sex ratio, the researchers realised they needed a much larger sample than in all previous studies. They turned to the UK Biobank, a biomedical database that contains the genetic and phenotypic information of about 500 000 British participants.

Analysing this data, the researchers identified a single nucleotide change named rs144724107 that is associated with a 10% increase in the probability of giving birth to a girl as opposed to a boy. But this nucleotide change is rare among the UK Biobank participants: About 0.5% of the participants carry this change. The nucleotide change is located near a gene named ADAMTS14, which is a member of the ADAMTS gene family known to be involved in spermatogenesis and fertilisation. The researchers also note that their discovery has not yet been confirmed in other samples.

The researchers also identified two genes, called RLF and KIF20B, that may also influence the sex ratio.

The study’s findings align with a theory in evolutionary biology called Fisher’s principle, which states that natural selection favours the genetic variant that increases the births of the rare sex. That is, if fewer males than females are born in a population, natural selection favours genetic variants that increase the number of males born, and vice versa. As a result, this selection yields a more or less even sex ratio in the population

“For Fisher’s principle to work, there must be mutations that influence the sex ratio,” Zhang said. “The fact that no genetic variation on human sex ratio had been identified has led some scientists to question the applicability of Fisher’s principle in humans.

“Our study shows that in fact, human data are consistent with Fisher’s principle and the reason no genetic variants of sex ratio had been discovered was the imprecision of the measure of a person’s offspring sex ratio.”

Next, the researchers hope to verify their findings in other samples – not an easy task, Zhang says, because of the large sample size requirement and the rareness of the identified genetic variant.

Source: University of Michigan