Category: Obstetrics & Gynaecology

New Cervical Cancer Test Catches Significantly More Cases

Female reproductive system. Credit: Scientific Animations CC4.0 BY-SA

Researchers have developed a simpler and more effective screening method for cervical cancer than the method used today. A comprehensive study published in Nature Medicine shows that the test detects significantly more cancers and precancerous stages.

Most countries have a very extensive cervical cancer screening program that starts with testing for different variants of the human papillomavirus (HPV) that causes cervical cancer. In the case of an HPV-positive test, this is followed by cytological analysis, the examination of gynaecological cell samples by microscopy, which is dependent on human interpretation.

The new molecular test WID-qCIN, which could replace the cytological analysis, can automatically analyse epigenetic changes in cells. These changes, where genes are switched on or off, are influenced by factors such as environment, lifestyle, and aging, and can increase the risk of cancer and other diseases.

Fewer invasive procedures

The current study by researchers at Karolinska Institutet and the University of Innsbruck included more than 28 000 women over the age of 30 who underwent screening in Stockholm between January and March 2017. The researchers analysed a total of 2377 HPV-positive samples with the WID-qCIN test combined with a test for two high-risk HPV types (HPV 16 and 18). In this way, they were able to detect 100% of all invasive cervical cancer and 93% of all serious precancerous lesions that occurred within a year of sampling.

In addition, the new test, in combination with the HPV 16/18 test, was able to predict 69% of all cancers and precancerous lesions up to six years after the sample was taken. This can be compared with only 18% with today’s screening method.

“By integrating the WID-qCIN test into our screening programs, we would be able to identify more cancer cases while reducing the need for invasive procedures,” says Joakim Dillner, Professor of Infectious Disease Epidemiology at Karolinska Institutet and co-author of the study.

A significant improvement 

When cell changes are detected in today’s screening program, the woman undergoes a vaginal examination, a so-called colposcopy, where the gynaecologist looks at the cervix with the help of a microscope and, if necessary, takes a biopsy. The biopsy involves a surgical procedure that, among other things, can lead to negative pregnancy outcomes like premature delivery. The results of the current study suggest that implementation of the WID-qCIN test could reduce the number of colposcopy examinations by 40%.

“This would mean a significant improvement compared to today’s screening methods, which were introduced in the 1960s,” says the study’s last author Martin Widschwendter, Professor at the University of Innsbruck (Austria) and visiting Professor at Karolinska Institutet. “With its simplicity and objective assessment, the WID-qCIN test can improve the effectiveness of these programs and support the global strategy to eliminate cervical cancer.” 

Source: Karolinska Institutet

Pre-menopausal Ovary Removal Linked to Reduced White Matter Integrity

Photo by Anna Shvets

Women who have their ovaries removed before menopause, particularly before the age of 40, have reduced white matter integrity in multiple regions of the brain later in life. The findings appear online in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

“We know that having both ovaries removed before natural menopause causes abrupt endocrine dysfunction, which increases the risk of cognitive impairment and dementia,” said Michelle Mielke, PhD, professor at Wake Forest University School of Medicine. “But few neuroimaging studies have been conducted to better understand the underlying mechanisms.”

For the study, the research team examined data from the Mayo Clinic Study of Aging to identify women over the age of 50 with available diffusion tensor imaging, a magnetic resonance imaging (MRI) technique that measures white matter in the brain. The cohort was comprised of:

  • 22 participants who had premenopausal bilateral oophorectomy (PBO) before age 40 
  • 43 participants who had PBO between the ages of 40 and 45
  • 39 participants who had PBO between the ages of 46 and 49
  • 907 participants who did not have PBO before the age of 50

“Females who had premenopausal bilateral oophorectomy before the age of 40 had significantly reduced white matter integrity in multiple regions of the brain,” said Mielke, the study’s corresponding author. “There were also trends in some brain regions such that women who had PBO between the ages of 40–44 or 45–49 years also had reduced white matter integrity, but many of these results were not statistically significant.”

Mielke said that 80% of participants who had their ovaries removed also had a history of oestrogen replacement therapy. Therefore, the study was not able to determine whether the use of oestrogen replacement therapy after PBO mitigated the effects of PBO on white matter integrity. She noted that the ovaries secrete hormones both before (primarily oestrogen, progesterone and testosterone) and after menopause (primarily testosterone and androstenedione). 

“Having both ovaries removed results in an abrupt decrease in both oestrogen and testosterone in women,” Mielke said. “Therefore, one possible explanation for our results is the loss of both oestrogen and testosterone.”

Mielke said additional research is needed to further understand how white matter changes are associated with cognitive impairment.

“While these findings are important for women to consider before having premenopausal bilateral oophorectomy for non-cancerous conditions, we need a larger and more diverse cohort of women to validate these results.”

Source: Wake Forest University School of Medicine

First Menstrual Periods are Arriving Earlier for Younger Generations

Photo by Marta Branco

The average age at menarche, the first menstrual period, has been decreasing among younger generations in the US, especially those belonging to racial minorities and lower socioeconomic statuses, according to a new study led by researchers at Harvard T.H. Chan School of Public Health. It also found that the average time it takes for the menstrual cycle to become regular is increasing.

The study, published in JAMA Network Open, is the latest publication from the Apple Women’s Health Study, a longitudinal study of menstrual cycles, gynaecological conditions, and overall women’s health conducted by Harvard Chan School, the National Institute of Environmental Health Sciences, and Apple.

“Our findings can lead to a better understanding of menstrual health across the lifespan and how our lived environment impacts this critical vital sign,” said co-principal investigator Shruthi Mahalingaiah, assistant professor of environmental, reproductive, and women’s health at Harvard Chan School.

While previous studies have shown trends towards earlier menarche over the past five decades, data has been limited on how these trends present within different racial groups and socioeconomic statuses. Additionally, few studies have had sufficient data to identify any trends regarding time to menstrual cycle regularity.

The researchers used the Apple Women’s Health Study’s large, diverse dataset to fill this research gap. The 71 341 participants who enrolled between November 2018 and March 2023 self-reported the age at which they first began menstruating and their race and socioeconomic status. The researchers divided the participants into five age brackets: born between 1950–1969, 1970–1979, 1980–1989, 1990–1999, and 2000-2005. Ages of menarche were defined as early (younger than 11 years old), very early (younger than 9), and late (ages 16 and above). A subset of participants (61 932) self-reported the time it took for their menstrual cycle to become regular and were divided into five categories: up to two years, between three and four years, longer than five years, hasn’t become regular, or became regular with use of hormones. Another subset (9865) provided their body mass index (BMI) at their age of menarche.

The study found that as birth year increased (meaning younger participants), average age at menarche decreased and time from menarche to menstrual cycle regularity increased. Among participants born from 1950–1969, the average age at menarche was 12.5 years, and the rates of early and very early menarche were 8.6% and 0.6%, respectively. Among participants born from 2000–2005, the average age of menarche was 11.9 years, and the rates of early and very early menarche were 15.5% and 1.4%, respectively. Across the two groups, the percentage of participants who reached menstrual cycle regularity within two years of menarche decreased from 76% to 56%. The researchers observed that these trends were present among all sociodemographic groups but were most pronounced among the participants who identified as Black, Hispanic, Asian, or mixed race, and who rated themselves as belonging to a low socioeconomic status.

The findings showed that BMI at age of menarche could explain part of the trend toward periods starting earlier. Other possible factors that might explain the trend include dietary patterns, psychological stress and adverse childhood experiences, and environmental factors such as endocrine-disrupting chemicals and air pollution.

“Continuing to investigate early menarche and its drivers is critical,” said corresponding author Zifan Wang, postdoctoral research fellow in Harvard Chan School’s Department of Environmental Health. “Early menarche is associated with higher risk of adverse health outcomes, such as cardiovascular disease and cancer. To address these health concerns – which our findings suggest may begin to impact more people, with disproportionate impact on already disadvantaged populations – we need much more investment in menstrual health research.”

The authors noted some limitations to the study, including that it relies heavily on retrospective self-reporting.

Source: Harvard T.H. Chan School of Public Health

Lifesaving Post-partum Haemorrhage Intervention is Highly Cost-effective

Photo by Anna Shvets on Pexels

A lifesaving package including early detection and bundled treatment for women who have post-partum haemorrhage has been found to incur minimal additional cost according to new analysis from 78 hospitals around the world.

In a paper published in Nature Medicine, a team of researchers working on the E-MOTIVE trial conducted an economic analysis to establish whether a package of interventions to objectively identify and treat post-partum haemorrhage (PPH) was cost effective.

Over 200 000 women from hospitals in Kenya, Nigeria, Tanzania and South Africa were included in the economic analysis of E-MOTIVE, with hospitals being randomly assigned to either the intervention or usual care groups. The intervention resulted in more than 1000 fewer PPH cases compared to the usual care group. The additional cost for E-MOTIVE was estimated to be, on average, an extra $0.30 per patient after adjustments for clinical factors including the proportion of patients with a clinical primary outcome event at each hospital, as well as for cluster and time-period considerations.

The economic analysis explored a range of costs for a key component of the E-MOTIVE package which is a calibrated blood collection drape, used for all women in the intervention group used to objectively measure blood loss. The analysis found that when the cost of the drape is around 1 USD, the average cost per patient could be comparable to usual care.

The cost of delivering the E-MOTIVE intervention could then be, on average, equivalent to usual care, which would represent a significant health benefit for women around the world

Professor Tracy Roberts

Tracy Roberts, Professor of Health Economics at the University of Birmingham and corresponding author of the study said:

“E-MOTIVE is clearly a cost-effective intervention for what is a lifesaving treatment for thousands of women around the world who may experience severe bleeding in childbirth. Our analysis of the E-MOTIVE trial shows that the costs incurred in delivering the package of treatments and the drape are on average minimal and represent really good value for money”.

“The drape forms a key part of the E-MOTIVE package, and should E-MOTIVE be widely adopted and the cost of drapes reduced to below $1, the economic benefits could be even more apparent. The cost of delivering the E-MOTIVE intervention could then be, on average, equivalent to usual care, which would represent a significant health benefit for women around the world.”

60% reduction in heavy bleeding

E-MOTIVE being found cost-effective comes after the publication of a landmark study published that found a 60% reduction in heavy bleeding for women experiencing PPH.

Postpartum haemorrhage (PPH) – defined as the loss of more than 500 mL of blood within 24 hours after birth – is the leading cause of maternal mortality worldwide. It affects an estimated 14 million women each year and results in around 70 000 deaths – mostly in low and middle-income countries – equivalent to 1 death every 6 minutes.

The study found that objectively measuring blood loss using a simple, low-cost collection device called a ‘drape’ and bundling together WHO-recommended treatments – rather than offering them sequentially – resulted in dramatic improvements in outcomes for women. Severe bleeding – when a woman loses more than a litre of blood after birth – was reduced by 60%, and they were less likely to lose their life.

There was also a substantial reduction in the rate of blood transfusions for bleeding, which is of particular importance in low-income countries where blood is a scarce and expensive resource.

Professor Arri Coomarasamy, who led the E-MOTIVE trial and is the Co-Director of the WHO Collaborating Centre on Global Women’s Health at the University of Birmingham said:

“This new approach to treating postpartum haemorrhage could radically improve women’s chances of surviving childbirth globally, helping them get the treatment they need when they need it.

“Time is of the essence when responding to postpartum bleeding, so interventions that eliminate delays in diagnosis or treatment should be gamechangers for maternal health. With this latest study showing that E-MOTIVE is extremely cost effective, and following WHO recommending the treatment bundle we hope that the intervention can quickly become the standard of care that will save many lives around the world.

Source: University of Birmingham

Metabolic Parameters Similar in Children Born via Frozen and Fresh Embryo Transfer

No differences in blood glucose, insulin, or cholesterol levels seen in children born via frozen versus fresh embryo transfer regardless of age, gender, or method of assisted conception

Children born via frozen embryo transfer have similar metabolic profiles to those born via fresh embryo transfer, according to a study published June 6th in the open-access journal PLOS Medicine by Linlin Cui and Zi-Jiang Chen from Shandong University, China, and colleagues.

Prior studies have shown inconsistent results on the long-term metabolic health impacts of assisted reproductive technology. Some have shown that children born via frozen embryo transfer have a higher risk of metabolic disorders, such as obesity, and unfavorable lipid profiles. Other studies have failed to find any significant metabolic differences between those born via frozen or fresh embryo transfer.

In this study, researchers compared the glucose and lipid profiles of more than 4000 children between 2 and 5 years of age – approximately half had been born via fresh embryo transfer and half had been born via frozen embryo transfer.

Researchers followed the children for an average of 3.6 years and assessed metabolic factors often associated with heart disease and diabetes, such as fasting blood glucose, insulin, cholesterol, and triglycerides.

They found no difference in any of the metabolic factors among children born via fresh embryo transfer and those born via frozen embryo transfer.

Given the relatively large number of participants in this study, the researchers were able to conduct subgroup analyses. After dividing the children into groups based on gender, age, embryo transfer state, and method of conception, there were still no differences in metabolic factors among the frozen and fresh embryo transfer groups.

The study provides more information to women and couples weighing the pros and cons of different techniques offered for assisted reproduction, but the researchers noted the need for additional data on the effect of assisted reproductive technology on long-term metabolic health.

The authors add, “Frozen embryo transfer shows no significant adverse effects on metabolic profiles in early childhood, providing crucial evidence for counseling couples undergoing assisted reproductive technology treatment on its safety.”

Provided by PLOS

New Research Dispels Morning Sickness Myths

Photo by Andrea Piacquadio

Late last year, geneticist Marlena Fejzo and colleagues made the discovery that morning sickness’s most serious presentation, hyperemesis gravidarum (HG), is caused by the hormone GDF15, not human chorionic gonadotropin as previously thought. In a peer-reviewed opinion article published in the journal Trends in Molecular Medicine, Fejzo dispels common morning sickness myths and discusses potential treatments, including sensitising people to GDF15 prior to pregnancy, similar to the way we treat allergies.

“HG can be life threatening and is associated with adverse outcomes that need to be taken seriously,” says Fejzo of the Keck School of Medicine of the University of Southern California. “Now that we know that GDF15 is the most likely cause of HG, we are on the cusp of having treatments that target this hormonal pathway and end the suffering.”

Myth 1: Severe morning sickness is harmless and normal

Pregnant people with HG are essentially starving, Fejzo says, and an increasing number of studies have demonstrated that this has serious short- and long-term clinical implications for both the parent and child. HG is a top predictor of postnatal depression, and 26% of pregnant people with HG report suicidal ideation while 18% meet the full criteria for post-traumatic stress disorder.

For the child, HG is associated with preterm birth, low birth weight, and later in life, autism spectrum disorder, ADHD, depression, social problems, in addition to an increased risk of childhood cancer and respiratory and cardiovascular disease. Still, pregnant people with the condition are often dismissed by their clinicians and families.

“It really is like a teratogen in pregnancy, a factor which interferes with normal foetal development, but it’s still not taken seriously by a lot of medical professionals,” Fejzo says. “A lot of people are brushed off and told, ‘oh that’s normal, it’s okay, just don’t take your pre-natal vitamins; you don’t need them.'”

At its most extreme, individuals with HG can develop Wernicke encephalopathy, a life-threatening swelling of the brain due to thymine (vitamin B1) deficiency. Since individuals with HG can have trouble even swallowing vitamins, the American College of Obstetricians and Gynecologists currently recommends that they replace broad spectrum prenatal vitamins with folic acid, but Fejzo warns that this is likely insufficient, and that thiamine supplementation is also warranted for individuals with HG.

“I believe all women who have hyperemesis should be given vitamin B1 to avoid this serious brain swelling that can lead to permanent brain damage and often leads to foetal death,” Fejzo says.

Myth 2: Morning sickness is caused by human chorionic gonadotropic hormone (hCG) or is psychosomatic

Though it was long thought that morning sickness is caused by hCG, the recent breakthrough has shown that HG’s main cause is actually the hormone GDF15, which is part of a normal stress response. Usually, GDF15 is expressed only in very small amounts, but during early pregnancy it spikes by a huge amount, then wanes, and finally rises again during the third trimester.

A recent Nature study co-authored by Fejzo showed that individuals who suffer from HG can have genetic variants that causes them to have lower levels of circulating GDF15 prior to pregnancy, which makes them extra sensitive when they become pregnant and are suddenly exposed to high levels. This finding has clinical implications for preventing and treating HG, since preliminary research suggests that it might be safe to manipulate GDF15 during or even prior to pregnancy.

“GDF15 may be safe to manipulate in pregnancy or even prior to pregnancy,” says Fejzo. “If we can increase levels of GDF15 before someone becomes pregnant, that might desensitise them, similar to how we try to desensitize people to allergens who have severe allergies,” says Fejzo. “And during pregnancy, we may be able to minimise or get rid of symptoms by blocking GDF15 or its receptors in the brain stem.”

Myth 3: Only humans experience morning sickness

Nausea and appetite loss during gestation is not a uniquely human trait – these symptoms have been observed throughout the animal kingdom, from monkeys, dogs, and cats, to chickens, vipers, and octopuses.

“I always think it’s interesting that the recommendation for cats is that if they’re unable to eat for a day, you should contact your veterinarian, but we don’t have that recommendation out there for women with hyperemesis,” says Fejzo. “If you call your doctor’s office and say you haven’t eaten for a day, they’ll say, ‘that’s normal’ and won’t do anything. There’s more proactive care for cats than humans.”

In addition to preventing ingestion of harmful foods, Fejzo speculates that pregnancy-induced nausea likely evolved to prevent dangerous foraging trips.

“This condition likely evolved because it was probably beneficial to avoid going out searching for food during pregnancy,” says Fejzo. “That may still be true for animals, but people don’t need this anymore, so let’s end the suffering once and for all if we can.”

Now, Fejzo is working toward developing and testing the proposed GDF15-based treatments. She also plans to investigate other genes and variants of GDF15 that might contribute to HG.

Source: Science Daily

Immune Dysfunction as a Possible Aspect of PCOS Pathology

Photo by Sora Shimazaki on Pexels

The study “Androgens Modulate the Immune Profile in a Mouse Model of Polycystic Ovary Syndrome” sheds light on immune dysfunction as a possible aspect of PCOS pathology, which could constitute a novel target for therapies.

The study shows that hyperandrogenism, a key characteristic of polycystic ovary syndrome (PCOS), affects immune cell populations in reproductive, metabolic, and immunological tissues in a PCOS-like mouse model. These findings are of great importance as it is known that immune dysfunction is an essential part of reproductive complications and metabolic disease, which are very common among women with PCOS. 

However, as the study shows that hyperandrogenism affects different tissues in unique ways, any possible treatments would have to be carefully tailored to target specific tissue dysfunctions. Since concurrent treatment with an androgen receptor antagonist prevented many changes in the mouse model we used in our study, combination therapies that include both anti-androgens and other drugs that target specific altered immune pathways could be explored.

Alteration of immune cells in adipose tissue

One of the most fascinating findings was the clear alterations of immune cells in adipose tissue, despite an unaltered fat mass of the androgen exposed mice. It is well known that immune cells in adipose tissue contribute to insulin resistance in overweight and obese individuals, but here we have an insulin resistant mouse model that mimics normal weight women with PCOS. The impact of androgens on immune cells in adipose tissue is therefore very interesting considering the high prevalence of insulin resistance and type-2 diabetes among normal weight women with PCOS. Another rather surprising finding was the drastic decrease of eosinophils in the uterus, as these don’t express the androgen receptor. This shows that androgens play a broader and more complex role in modulating the immune environment than only through direct androgen receptor activation on immune cells. 

The next step will be to dissect the underlying mechanisms of the immune alterations, and to assess if these do contribute to the reproductive complications and metabolic comorbidities of PCOS. This will include further characterisation of immune cell changes to understand how their function could be affected and link these to reproductive and metabolic mechanisms. We also want to understand how the effect of androgens on eosinophils and mature NK cells is mediated, since neither of them expresses the androgen receptor. 

Source: Karolinska Institutet

Most Young Breast Cancer Survivors can Still Have Children

Photo by SHVETS production

A new study by Dana-Farber Cancer Institute investigators, which tracked nearly 200 young women treated for breast cancer, found that the majority of those who tried to conceive during a median of 11 years after treatment were able to become pregnant and give birth to a child.

The findings, to be presented at the 2024 Annual Meeting of the American Society of Clinical Oncology (ASCO), are particularly noteworthy because they answer several questions left open by previous studies of pregnancy and live-birth rates among breast cancer survivors, the study authors say.

“Earlier studies were limited because they included select subgroups of patients, followed patients for a relatively short period of time, and didn’t ask participants, during the study period, if they had attempted pregnancy,” says the study’s senior author, Ann Partridge, MD, MPH, the founder and director of the Program for Young Adults with Breast Cancer at Dana-Farber. “This study was designed to address those gaps by tracking pregnancy and live birth rates among a group of breast cancer survivors and patients who indicated they’d attempted to conceive following their cancer diagnosis.”

The patients in the study were participants in the Young Women’s Breast Cancer Study, which is tracking the health of a group of women diagnosed with breast cancer at or under age 40. Of 1213 eligible participants, 197 reported an attempt of pregnancy over a median follow-up period of 11 years. Within this latter group, the median age at the time of diagnosis was 32 years, and most were diagnosed with hormone receptor-positive breast cancer. Participants were periodically surveyed about whether they had tried to become pregnant and whether they had conceived and given birth.

Over the course of the study, 73% of women attempting to conceive achieved a pregnancy and 65% had a live birth, researchers found. Those who opted for fertility preservation by egg/embryo freezing before cancer treatment tended to have a higher live birth rate, while older participants tended to have lower pregnancy and live birth rates

Participants in the study had breast cancers ranging from stage 0, which are non-invasive and confined to the inside of the milk duct, to stage III, in which the cancer has spread to the lymph nodes. There was no statistically significant association with stage of the disease at diagnosis and achieving a pregnancy or live birth.

“For many young women with breast cancer, the ability to have children following treatment is a major concern,” says the study’s first author, Kimia Sorouri, MD, MPH, of Dana-Farber. “The findings of our study can be helpful when counselling patients about fertility issues. The finding that egg/embryo freezing before treatment was associated with a higher live birth rate underscores the need for accessibility to fertility preservation services for this population.”

Source: Dana-Farber Cancer Institute

Health and Economic Benefits of Breastfeeding Quantified

Among half a million Scottish infants, those exclusively breastfed were less likely to use healthcare services and incurred lower costs to the healthcare system

Photo by Wendy Wei

Breastmilk can promote equitable child health and save healthcare costs by reducing childhood illnesses and healthcare utilisation in the early years, according to a new study published this week in the open-access journal PLOS ONE by Tomi Ajetunmobi of the Glasgow Centre for Population Health, Scotland, and colleagues.

Breastfeeding has previously been found to promote development and prevent disease among infants. In Scotland – as well as other developed countries – low rates of breastfeeding in more economically deprived areas are thought to contribute to inequalities in early childhood health. However, government policies to promote child health have made little progress and more evidence on the effectiveness of interventions may be needed.

In the new study, researchers used administrative datasets on 502,948 babies born in Scotland between 1997 and 2009. Data were available on whether or not infants were breastfed during the first 6-8 weeks, the occurrence of ten common childhood conditions from birth to 27 months, and the details of hospital admissions, primary care consultations and prescriptions.

Among all infants included in the study, 27% were exclusively breastfed, 9% mixed fed and 64% formula fed during the first 6-8 weeks of life. The rates of exclusively breastfed infants ranged from 45% in the least deprived areas to 13% in the most deprived areas.

The researchers found that, within each quintile of deprivation, exclusively breastfed infants used fewer healthcare services and incurred lower costs compared to infants fed any formula milk. On average, breastfed infants had lower average costs of hospital care per admission (£42) compared to formula-fed infants (£79) in the first six months of life and fewer GP consultations (1.72, 95% CI: 1.66 – 1.79) than formula-fed infants (1.92 95% CI: 1.88 – 1.94). At least £10 million of healthcare costs could have been avoided if all formula-fed infants had instead been exclusively breastfed for the first 6-8 weeks of life, the researchers calculated.

The authors conclude that breastfeeding has a significant health and economic benefit and that increasing breastfeeding rates in the most deprived areas could contribute to the narrowing of inequalities in the early years.

Provided by PLOS

Birth by C-section More than Doubles Odds of Measles Vaccine Failure

Photo by Christian Bowen on Unsplash

A study by the University of Cambridge, UK, and Fudan University, China, has found that a single dose of the measles jab is up to 2.6 times more likely to be completely ineffective in children born by C-section, compared to those born naturally.

Failure of the vaccine means that the child’s immune system does not produce antibodies to fight against measles infection, so they remain susceptible to the disease.

A second measles jab was found to induce a robust immunity against measles in C-section children.

Measles is a highly infectious disease, and even low vaccine failure rates can significantly increase the risk of an outbreak.

A potential reason for this effect is linked to the development of the infant’s gut microbiome — the vast collection of microbes that naturally live inside the gut. Other studies have shown that vaginal birth transfers a greater variety of microbes from mother to baby, which can boost the immune system.

“We’ve discovered that the way we’re born – either by C-section or natural birth – has long-term consequences on our immunity to diseases as we grow up,” said Professor Henrik Salje in the University of Cambridge?’s Department of Genetics, joint senior author of the report.

He added: “We know that a lot of children don’t end up having their second measles jab, which is dangerous for them as individuals and for the wider population.

“Infants born by C-section are the ones we really want to be following up to make sure they get their second measles jab, because their first jab is much more likely to fail.”

The results are published today in the journal Nature Microbiology.

At least 95% of the population needs to be fully vaccinated to keep measles under control but the UK is well below this, despite the Measles, Mumps and Rubella (MMR) vaccine being available through the NHS Routine Childhood Immunisation Programme.

An increasing number of women around the world are choosing to give birth by caesarean section: in the UK a third of all births are by C-section, in Brazil and Turkey over half of all children are born this way.

“With a C-section birth, children aren’t exposed to the mother’s microbiome in the same way as with a vaginal birth. We think this means they take longer to catch up in developing their gut microbiome, and with it, the ability of the immune system to be primed by vaccines against diseases including measles,” said Salje.

To get their results, the researchers used data from previous studies of over 1500 children in Hunan, China, which included blood samples taken every few weeks from birth to the age of 12. This allowed them to see how levels of measles antibodies in the blood change over the first few years of life, including following vaccination.

They found that 12% of children born via caesarean section had no immune response to their first measles vaccination, as compared to 5% of children born by vaginal delivery. This means that many of the children born by C-section did still mount an immune response following their first vaccination.

Two doses of the measles jab are needed for the body to mount a long-lasting immune response and protect against measles. According to the World Health Organization, in 2022 only 83% of the world’s children had received one dose of measles vaccine by their first birthday – the lowest since 2008.

Salje said: “Vaccine hesitancy is really problematic, and measles is top of the list of diseases we’re worried about because it’s so infectious.”

Measles is one of the world’s most contagious diseases, spread by coughs and sneezes. It starts with cold-like symptoms and a rash, and can lead to serious complications including blindness, seizures, and death.

Before the measles vaccine was introduced in 1963, there were major measles epidemics every few years causing an estimated 2.6 million deaths each year.

The research was funded by the National Natural Science Foundation of China.

The original text of this story is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Licence.

Source: University of Cambridge