Paracetamol use in pregnancy was not linked to autism or ADHD, while separate research found reproductive differences in girls exposed before birth.

One study analysed health records from more than 120,000 children and found no increased risk of autism following prenatal paracetamol exposure.

A separate analysis of nearly 100,000 children also found no increased risk of ADHD among those born to mothers who used the painkiller during pregnancy.

Researchers from the Hong Kong Hospital Authority examined electronic health records covering pregnancies between January 2001 and December 2023.

The autism analysis included 124,333 children, who were nine years old on average and split almost evenly between males and females. There were 3,445 autism diagnoses, representing 2.8 per cent of the group.

The ADHD analysis involved 97,285 children, who were seven years old on average and also split evenly between males and females. There were 5,168 ADHD diagnoses, representing 5.3 per cent.

Women prescribed paracetamol during pregnancy were more likely to be older and have pre-existing conditions including psychiatric disorders, as well as reasons for taking the drug such as infection, fever or chronic pain.

No association was found between prenatal paracetamol exposure and either autism or ADHD.

The findings did not differ according to the trimester in which paracetamol was taken or whether use was intermittent or daily. Advanced maternal age, defined as pregnancy in women over 35, did not alter the findings.

The researchers wrote: “Paracetamol remains a safe and essential analgesic [pain reliever] and antipyretic [fever reducer] during pregnancy, whereas alternatives, such as NSAIDs and opioids carry well-documented risks.

“Unwarranted reluctance to use paracetamol could lead to undertreatment of pain and fever, or the use of more harmful alternatives, both posing risks to the pregnancy and developing fetus.”

The authors said women should assess paracetamol use with guidance from their doctor.

A separate study involving 685 pregnant women without pre-existing conditions and 302 infant daughters found associations between prenatal paracetamol exposure and differences in reproductive organs and hormone levels.

Researchers from Copenhagen University Hospital enrolled the women during their first trimester and assessed them during the first trimester, third trimester and again when their babies were three months old.

At around three months, infants experience a temporary rise in reproductive hormones sometimes called mini-puberty.

Pregnant participants completed questionnaires every two weeks about their use of pain medicines including paracetamol. Infant girls underwent ultrasound scans of their reproductive organs and blood tests to measure hormone levels.

Researchers also examined a separate group of 1,210 girls followed from infancy to adolescence whose mothers reported paracetamol use during the third trimester.

Three-month-old girls exposed to paracetamol before birth had an average 40 per cent smaller ovarian volume, 13 per cent smaller uterine volume and 23 per cent fewer ovarian follicles.

Girls exposed during the first trimester also had lower levels of Anti-Müllerian hormone, a marker of ovarian function.

Among the older girls, those exposed before birth were more likely to have smaller uteruses at puberty and smaller ovaries during their teenage years.

Dr Margit Bistrup Fischer, lead study author and postdoctoral researcher in the Department of Growth and Reproduction at Rigshospitalet hospital in Denmark, said: “Animal studies have demonstrated that impaired formation of ovarian follicles can lead to reduced fertility and earlier reproductive aging.

“Whether the differences observed in our study have implications for fertility and age at menopause in humans remains unknown and will require long-term follow-up of the girls in our cohort.”

She cautioned that women who had used paracetamol during pregnancy “should not be alarmed by our findings”, as the study found associations rather than direct causation and outcomes for individual women and children are unclear.

“Importantly, our study does not evaluate whether [acetaminophen] causes reproductive problems, nor does it provide evidence that prenatal exposure affects future fertility or age at menopause,” she said.

“Although we observed similar associations in an independent cohort, long-term follow-up is needed to determine whether these early-life differences have any clinical significance later in life.”

Targeting CD1d altered immune cells slowed tumour growth and improved immunotherapy responses in mouse models of breast cancer, researchers found.

The findings suggest blocking the molecule could make the environment around breast tumours more favourable to anti-cancer immune responses.

Further work is needed to understand how these immune changes occur and how the approach could be safely used in patients.

Researchers from King’s College London, the Francis Crick Institute and University College London investigated how immune cells inside breast tumours influence cancer growth.

They focused on myeloid cells, a group of immune cells found in large numbers within tumours that can either support an immune attack against cancer or contribute to tumour growth and immune evasion.

The team examined CD1d, a molecule found on the surface of myeloid and other immune and tissue cells that helps regulate immune responses.

When CD1d was genetically removed from cells in a mouse model of breast cancer, the mice were more resistant to tumour growth. Researchers also saw changes in myeloid cell populations, including increased activity among cells that can help attack cancer.

The team then blocked CD1d using an antibody and again observed changes in myeloid cells and slower tumour growth. Blocking CD1d also improved responses to immunotherapy in the mouse model.

Researchers used single-cell RNA sequencing, a technique that examines gene activity in individual cells, to investigate the immune changes in more detail.

They identified a population of myeloid cells called monocytes that expressed genes associated with inflammation, an important part of the immune response. These cells were particularly important in restricting tumour growth in the mouse models.

A similar pattern of gene activity was identified in data from human breast cancer tumours. Its presence in myeloid cells was associated with positive responses to immunotherapy in breast cancer patients.

However, the findings in people were based on gene expression data and did not test CD1d-targeting treatment in patients.

Professor Patricia Barral, professor of immunobiology at King’s College London and senior author of the study, said: “Many breast cancers do not respond well to current immunotherapies.

“Our findings reveal a previously unrecognised mechanism by which immune cells within tumours are regulated.

“While CD1d is best known for helping immune cells recognise lipid molecules, we found that it also plays a role in shaping the behaviour of myeloid cells within tumours.

“These findings suggest that targeting the immune cells that surround and support tumours could boost anti-cancer immunity and potentially improve treatment responses in the future.”

Researchers now plan to investigate how the immune changes occur and how they can be safely harnessed in patients.

They also want to examine whether targeting CD1d could enhance existing treatments and influence treatment responses in different cancer types.

The work was supported by UKRI BBSRC, Breast Cancer Now and the Cancer Research UK City of London Centre.

Menopause is often absent from women’s electronic health records, a study of nearly 396,000 women has found.

Researchers found menopause appeared almost seven times more often in participant surveys than in electronic health records (EHRs).

The findings suggest important reproductive health information, including age at menopause, may often be missing from health records used for research.

Audrey Hendricks, associate professor of bioinformatics at CU Anschutz and the study’s principal investigator, said: “Ultimately, we cannot study what we do not measure. We cannot treat what we do not know.

“Menopause has enormous implications for women’s health, but if we don’t consistently capture when menopause occurs and other important reproductive health information, we limit our ability to understand how this transition affects disease risk and health outcomes.”

Researchers at the University of Colorado Anschutz analysed data from women taking part in the National Institutes of Health’s All of Us Research Program.

They compared menopause information reported by participants in surveys with menopause diagnoses recorded in their electronic health records.

Around 193,000 menopause observations were identified in survey data, compared with approximately 28,000 diagnoses in EHR data.

Menopause was documented in electronic health records for only about 7 per cent of women in the dataset.

Nearly all participants with a menopause diagnosis recorded in their EHR also reported menopause in survey data. However, substantially fewer women had menopause documented in their health records.

Other important information was also frequently unavailable, including age at menopause, which researchers may use when examining links between menopause and chronic disease risk.

Menopause is a physiological transition that can affect cardiometabolic health and many other aspects of women’s health.

Researchers said relatively little is known about how factors including the timing and type of menopause influence health outcomes across diverse populations.

Large-scale programmes such as All of Us combine participant surveys, electronic health records and genomic data, but menopause-related research depends on relevant reproductive health information being available.

Missing menopause information can make it harder to investigate how the transition relates to health and disease.

The findings may also help researchers using All of Us data define menopause-related study populations, design studies and estimate how many participants are needed.

Hendricks said: “We have an enormous opportunity to use large-scale datasets to understand women’s health across the menopause transition and to identify who may be at greater risk for disease.

“But we need to make sure that the information researchers need is actually being collected.

“We must do a better job of capturing women’s health information, including reproductive health and measures related to menopause.”

Researchers said more complete and consistent collection of menopause and reproductive health information could help future studies examine factors such as age at menopause and their relationship with disease risk and health outcomes.