Medical Bulletin 27/August/2026

Here are the top medical news for today:

Bacteria in Semen May Raise Risk of Poor Pregnancy Outcomes: Study

Infertility has historically been viewed largely as a female health issue, despite conception depending on both partners. New research is highlighting another potential contributor to fertility: the microbiome of semen.

A recent Danish study published in The Lancet Obstetrics, Gynaecology, and Women’s Health investigated the gut, vaginal and semen microbiomes of couples undergoing fertility treatment and couples being evaluated for recurrent pregnancy loss.

Researchers analyzed samples from 353 women and 191 male partners using deep shotgun metagenomic sequencing to identify the microorganisms present in the different body sites.

The study found that an imbalance in semen bacteria, known as seminal V-dysbiosis, was present in about 24% of men in the IVF group and 41% of men in the recurrent miscarriage group.

Among couples undergoing IVF, outcomes also differed depending on the male partner’s semen microbiome. Around 85% of couples achieved a live birth when the male partner had a balanced semen microbiome, compared with 57% when seminal dysbiosis was present.

The semen microbiome refers to the community of microorganisms living in seminal fluid. It includes bacteria such as Lactobacillus, Prevotella and Pseudomonas. Once considered sterile, semen is now known to contain a diverse microbial community originating from areas including the reproductive and urinary tracts.

Certain microbial patterns may be associated with sperm health. Higher levels of Lactobacillus have been linked with better sperm movement and concentration, while an overgrowth of certain bacteria, including Prevotella, Ureaplasma and some Pseudomonas strains, has been associated with poorer sperm quality and motility.

The findings suggest that male reproductive health and the semen microbiome could be important factors in fertility treatment outcomes. However, the study demonstrates an association and does not prove that correcting seminal dysbiosis will improve IVF success. Further research is needed to determine whether microbiome-based testing or treatments could eventually become part of fertility care.

REFERENCE: Behrendt-Møller I, Krog M, Myers P et al.; Gut, vaginal, and seminal microbiomes in couples with infertility or recurrent pregnancy loss: a two-cohort prospective study of reproductive outcomes; The Lancet Obstetrics, Gynaecology, & Women’s Health, 2026; DOI: 10.1016/S3050-5038(26)00213-X

Global Study Reveals Air Pollution Can Harm Multiple Organs Beyond Lungs

Air pollution is often associated with coughing, breathing difficulties and lung disease. However, a new global study, published in Nature Health, suggests its impact may extend much further, linking long-term exposure to air pollutants with millions of cancer cases worldwide.

Researchers analysed cancer and air pollution data from 952 locations between 2000 and 2020, covering 109 million cancer cases. The study examined three major pollutants: fine particulate matter PM2.5, ozone and nitrogen dioxide.

PM2.5 emerged as the biggest contributor. Researchers estimated that long-term exposure was associated with around 8.82 million cancer cases during the study period. Nitrogen dioxide was linked to approximately 6.67 million cases, while ozone was associated with about 2.59 million.

PM2.5 particles are 2.5 micrometres or smaller, allowing them to penetrate deep into the lungs and potentially enter the bloodstream. Every 10 micrograms per cubic metre increase in long-term PM2.5 exposure was associated with a 16% higher risk of all cancers. Comparable increases were 11.7% for nitrogen dioxide and 4.23% for ozone.

The strongest association was seen with cancers of the respiratory system. Researchers estimated that around 17.9% of tracheal, bronchial and lung cancer cases could potentially be prevented by eliminating PM2.5 exposure.

However, the potential effects appeared to extend beyond the lungs. PM2.5 exposure was also associated with cancers affecting the thyroid, oesophagus, colon and rectum, breast, kidney and bladder. A 10 micrograms per cubic metre increase was linked to 17.9% higher kidney cancer risk and 21.1% higher bladder cancer risk.

Researchers suggest that oxidative stress, DNA damage and disruption of immune responses could contribute to these associations.

The findings add to evidence that cleaner air is not only an environmental priority but also an important long-term cancer prevention and public health concern.

REFERENCE: Zhang, G., Li, Y., Li, A. et al. Global cancer burden associated with long-term exposure to ambient air pollution. Nat. Health (2026). https://doi.org/10.1038/s44360-026-00180-4

Women With Type 2 Diabetes More Likely to Develop Mental Health Conditions: Study

People with type 2 diabetes may face different health complications depending on their sex, with women more likely to develop mental health conditions while men face greater risks of cardiovascular and kidney problems, according to a study published in PLOS Medicine.

Researchers from Queen Mary University of London analysed anonymised health records of 28,720 people in the UK who developed type 2 diabetes between 2010 and 2020. Men accounted for 62% of the participants and had a median age of 54 at diagnosis, while women were generally older when diagnosed.

During the years following diagnosis, 39% of participants experienced at least one major health event. However, researchers found clear differences in the types and timing of complications between men and women.

Women were more likely to develop mental health conditions, including depression and anxiety. Mental health complications occurred in 8.1% of women compared with 5.3% of men. Women were also more likely to follow disease trajectories that ultimately resulted in death.

Men, meanwhile, had higher proportions of cardiovascular disease, end-stage renal disease and hypertension. Cardiovascular disease affected 8.4% of men compared with 5.3% of women. Hypertension was reported in 21.1% of men and 20.2% of women.

The researchers also found that women used more healthcare services and long-term prescriptions than men, which may partly explain differences in recorded diagnoses.

Despite the differences, hypertension remained the most frequent health event across both sexes and all age groups. People who developed both type 2 diabetes and a mental health condition also faced a higher risk of premature death.

The researchers said the findings highlight the need for more personalised diabetes care based on sex and age. Younger women may benefit from routine psychological screening, while men could require earlier monitoring for cardiovascular and kidney complications.

The study suggests that recognising these differences could help doctors identify complications earlier and improve long-term outcomes for people living with type 2 diabetes.

REFERENCE: Fabiola Eto, et al.; Sex differences in trajectories to cardio-renal and mental health outcomes following the onset of type 2 diabetes: An observational cohort study using multi-state analysis in the UK Clinical Practice Research Datalink; PLOS Medicine; DOI: 10.1371/journal.pmed.1005196