Pregnancy
Boosting immune cell tolerance may help prevent early pregnancy loss
Recurrent pregnancy loss can be devastating and exert a major impact on women, their partners, and society more broadly, but currently there are few options for effective therapies.
Over several years, there has been mounting evidence that a deficiency in special immune cells called T-regulatory (Treg) cells, which are essential for preparing the uterus for receptive embryo implantation, are a factor in early pregnancy loss.
A new study in The American Journal of Pathology, details evidence in a pre-clinical animal model that boosting these cells improves the chance of healthy pregnancy. The work raises the prospect of evaluating this intervention in women who are prone to experience early pregnancy loss, a common condition affecting natural conception and women undergoing in vitro fertilization (IVF).
Lead investigator Sarah A. Robertson, PhD, The Robinson Research Institute and School of Biomedicine, the University of Adelaide, Australia, explained: “Previous studies have found low numbers of Treg cells in women who experienced early pregnancy loss as well as changes that lead Treg cells to have functional problems that are reminiscent of autoimmune diseases.
“This can impair the implantation process and suppress development of the early placenta. Therefore, Treg cells provide an attractive target for interventions to improve maternal immune tolerance and protect against pregnancy disorders caused by immune imbalance in at-risk women.”
The researchers utilized a mouse model of early pregnancy loss to test a new candidate treatment intervention in which the cytokine interleukin-2 (IL-2) is combined with specific antibodies to target Treg cells. Like humans with recurrent pregnancy loss, the mice have an immune defect that arises at conception and results in later feotal loss.
The researchers administered the IL-2 antibody complex (called IL-2/JES6-1) in the time between conception and embryo implantation to the miscarriage-prone mice and also in mice that have had healthy pregnancies. They observed significant changes to the number and phenotype of the Treg cells in the uterus, blood, and other tissues in both groups of mice.
The expanded pool of Treg cells exhibited features that are characteristic of robust pregnancy tolerance and were effective in preventing generation of detrimental effector T cells that threaten pregnancy success. Importantly, the miscarriage-prone mice showed markedly improved pregnancy outcomes after treatment, and their miscarriage rate was consistently reduced from 30 per cent to 11 per cent, which is within the normal range for mice.
Professor Robertson added: “The results show that efficacy of the IL-2/JES6-1 treatment might be achieved with lower doses, which will likely be important as we consider how to translate the findings to human application.
“Another notable observation was that treatment in very early pregnancy, even before the embryos commence implantation, has a profound effect on the progression of the pregnancy with lasting benefit into late gestation.
“This is consistent with growing evidence pointing to embryo implantation and early placental development being the turning point for pregnancy success.”
The study demonstrates the potential of targeting Treg cells and provides pivotal evidence to justify human studies; however, it will be important to undertake clinical trials to assemble evidence of safety and benefit in humans before the treatment can be recommended.
The Royal College of Midwives (RCM) has referred to the women’s health strategy as a ‘missed opportunity’ to address maternity services.
The renewed strategy was released by the government this week, with the aim of putting women’s experiences at the centre of care and ensuring they are “better heard and served”.
However, the government stated that because of ongoing investigations into maternity services across the country, the strategy “does not seek to address safety in maternity and neonatal services”.
The RCM described this as a “missed opportunity” and urged the government to ensure that, following the inquiries, maternity is placed “at the very heart” of the strategy.
Gill Walton, RCM chief executive, said the college was “deeply disappointed” that maternity services “do not feature as a headline priority” in the renewed strategy.
She said: “This is a significant missed opportunity and one that is very difficult to understand.
“Pregnancy, birth and the postnatal period are not a footnote in women’s health – they are one of the most significant and consequential phases of a woman’s life.
“A strategy that treats maternity as an afterthought is not truly a women’s health strategy at all. It is exactly the kind of thinking that has allowed maternity services to reach the point they are at today.”
Walton acknowledged that the strategy contained commitments on ensuring women’s voices shape their care, on supporting families through pregnancy loss and on the principle that services should be held accountable when they fail to listen to women.
She added: “But a strategy that addresses one part of women’s health while leaving maternity care behind is only doing half the job.”
Walton urged the government to ensure that this is addressed when the ongoing investigations into maternity care conclude, with any recommendations placed “at the very heart of this strategy with the seriousness and urgency that women, families and midwives deserve”.
In the foreword to the renewed plans, health and social care secretary Wes Streeting referred to the ongoing independent National Maternity and Neonatal Investigation as action being taken by the government to improve safety in maternity services.
The strategy also refers to the new National Maternity and Neonatal Taskforce, chaired by Streeting, which aims to help deliver “safer, more equitable care” for women, babies and families.
The foreword said that, because of ongoing initiatives, it was “important that this work continues without restriction and that the government can properly respond to the findings”.
It added: “This renewed women’s health strategy therefore does not seek to address safety in maternity and neonatal services other than that related to women’s health before and during pregnancy and the actions we are taking immediately to improve maternity and neonatal care.”
The strategy does, however, include plans to prioritise health education in schools, communities and healthcare settings to “empower women” with the “knowledge and tools they need to help control their fertility” and “prepare for the best pregnancy outcomes.
It also promises to provide women with access to “safe and high-quality contraception, abortion care, fertility services, preconception care and support after pregnancy loss in convenient settings.
Article produced in association with London Pregnancy Clinic and Jeen Health
For the majority of couples planning a pregnancy, genetic testing is not something they think about until a problem arises.
Pre-conception genetic carrier screening challenges this approach by identifying risk before pregnancy begins.
As panel sizes have grown and at-home testing options have become widely available, carrier screening is transitioning from a niche clinical referral into a mainstream component of reproductive planning.
What Carrier Screening Tests For
Being a carrier of a genetic condition means carrying one copy of a variant in a gene associated with that condition, without being affected by it.
In most cases, carriers are entirely unaware of their status.
The clinical significance of carrier status emerges when both members of a couple carry a variant in the same gene: in this scenario, each pregnancy carries a one in four chance of resulting in a child who inherits two copies of the variant and is affected by the condition.
The conditions most frequently included in expanded carrier screening panels include cystic fibrosis, spinal muscular atrophy (SMA), fragile X syndrome, sickle cell disease, and a range of metabolic and enzyme deficiency disorders.
The Beacon 787 carrier test, offered by Jeen Health, screens for 787 conditions from a single sample, making it one of the most comprehensive panels currently available to UK families.
Who Is Most Likely to Benefit
Any couple planning a pregnancy can consider carrier screening. It is particularly relevant for:
- Couples with a family history of a known inherited condition
- Those from populations with higher carrier frequencies for specific conditions, including Ashkenazi Jewish, South Asian and African communities
- Couples pursuing fertility treatment, where genetic information informs treatment planning
- Those who wish to have the most complete picture of their reproductive health before conception
Importantly, being a carrier of a condition does not mean a child will be affected. It means there is a defined statistical risk that can be quantified, discussed and planned for with appropriate clinical support.
How the Test Is Performed
Carrier screening is typically carried out on a blood or saliva sample.
For at-home options such as the testing offered by Jeen Health, a cheek swab collection kit is dispatched to the patient, the sample is returned by post, and results are delivered digitally within a defined turnaround period.
In-clinic carrier testing may use a blood draw and provides the advantage of immediate access to a clinical consultation at the point of result delivery.
London Pregnancy Clinic offers genetics counselling through its partnership with Jeen Health, allowing couples to receive and contextualise carrier test results with expert support.
Genetic counselling before and after testing is recommended by Genomics England as a standard component of any genomic testing pathway.
What Happens If Both Partners Are Carriers
If both partners are identified as carriers for the same autosomal recessive condition, they are typically offered further counselling to discuss their options.
These may include proceeding naturally with an awareness of the risk, using prenatal diagnosis (CVS or amniocentesis) during pregnancy to test the fetus, or pursuing preimplantation genetic testing (PGT) in the context of IVF, which allows unaffected embryos to be selected before transfer.
The purpose of identifying carrier status before pregnancy is to give couples time to consider these options without the added pressure of an ongoing pregnancy.
Knowledge of carrier status does not remove reproductive choices; it expands the information available when making them.
The Role of Pre-Conception Services
Carrier screening sits within a broader category of pre-conception care that includes fertility assessments, general health optimisation and, where relevant, management of existing conditions before pregnancy begins.
London Pregnancy Clinic offers pre-conception services encompassing fertility investigations, genetics counselling and carrier testing as part of an integrated 0th trimester approach, allowing couples to address genetic and clinical risk factors before their pregnancy starts rather than after.
Disclaimer: This article is produced for informational purposes only and does not constitute medical advice, diagnosis or treatment.
Clinical guidance referenced reflects published NHS, NICE and RCOG standards as at March 2026. Individual circumstances vary; readers are advised to consult a qualified healthcare professional before acting on any information in this article.
This piece was produced in association with London Pregnancy Clinic and Jeen Health, which provided background clinical information for editorial purposes.
Hyperlinks to external sources are included for reference only and do not represent an endorsement of any product, service or organisation.
Article produced in association with London Pregnancy Clinic and Jeen Health
For many years, formal clinical involvement in a pregnancy began at the point of confirmation, typically around eight to ten weeks.
The concept of the ‘0th trimester’ represents a shift in thinking: that the period before conception is itself a clinically significant window, during which health optimisation, risk identification and informed planning can meaningfully improve pregnancy outcomes.
Guidance from Tommy’s and the NHS both recommend pre-conception care as part of responsible reproductive health management.
What Pre-Conception Care Involves
Pre-conception care is not a single test or appointment. It is a structured approach to assessing and optimising a woman’s health before she attempts to conceive.
The NHS guidance on planning a pregnancy recommends a range of measures including taking folic acid, reviewing medications for safety in pregnancy, ensuring immunity to rubella and chickenpox, and addressing pre-existing conditions such as thyroid disorders, diabetes or high blood pressure before conception occurs.
General pre-conception assessments typically include blood pressure and BMI review, full blood count and iron levels, thyroid function, immunity screening (rubella, varicella), vitamin D status and cervical screening if overdue.
For women with existing conditions, specialist review before pregnancy is often more valuable than specialist referral during it.
Fertility Investigations as Part of the 0th Trimester
For women who are planning a pregnancy but have concerns about fertility, pre-conception investigations provide information that informs planning rather than leaving uncertainty unaddressed.
Clinics offering 0th trimester services, including London Pregnancy Clinic, provide investigations including hysterosalpingo-contrast-sonography (HyCoSy) to assess tubal patency, follicle tracking scans, anti-Mullerian hormone (AMH) testing to estimate ovarian reserve, and endometrial assessment.
These tests do not guarantee conception but they provide a clinical foundation from which fertility decisions can be made with better information.
Genetic Assessment in Pre-Conception Care
The genetic dimension of pre-conception care is increasingly central to a thorough 0th trimester assessment.
Genetic carrier screening before pregnancy allows couples to identify their carrier status for conditions such as cystic fibrosis, SMA and a range of other inherited disorders before conception, giving them time to consider their options with appropriate clinical support.
At-home carrier testing offered by Jeen Health provides access to comprehensive carrier screening without the need for a clinical referral.
Couples collect their sample at home and receive results within a defined timeframe.
When both partners carry a variant in the same gene, the result can be followed up with genetic counselling via clinics such as London Pregnancy Clinic, where clinical specialists can contextualise the findings and explain the available options.
Lifestyle and Nutritional Factors
Pre-conception health is not limited to clinical testing.
Lifestyle factors including physical activity levels, nutritional status, alcohol consumption and smoking all influence fertility and early fetal development.
Pre-conception care provides an opportunity to address these factors proactively rather than as an afterthought following a positive test.
Folic acid supplementation, recommended at 400 micrograms per day in the pre-conception period and the first trimester, is one of the most evidence-supported interventions available.
Why Timing Matters
Many of the interventions that benefit pregnancy are most effective when started before conception rather than after.
Addressing thyroid dysfunction, normalising blood pressure, treating iron deficiency anaemia, and identifying genetic risks all have a higher potential impact when managed from the outset rather than detected at the first antenatal appointment.
The 0th trimester framework provides a way of thinking about pre-conception care as a structured medical period with its own clinical agenda, rather than simply a waiting room for the first trimester.
What a Pre-Conception Appointment Might Look Like
A comprehensive pre-conception assessment with a specialist provider would typically cover a clinical consultation reviewing medical and family history, a pelvic ultrasound scan, blood tests for general health markers and fertility hormones, cervical health review if indicated, and a discussion of genetic risk including a recommendation for carrier screening if appropriate.
For couples with specific concerns about fertility or genetic history, specialist investigations can be added to this baseline assessment.
Disclaimer: This article is produced for informational purposes only and does not constitute medical advice, diagnosis or treatment.
Clinical guidance referenced reflects published NHS, NICE and RCOG standards as at March 2026. Individual circumstances vary; readers are advised to consult a qualified healthcare professional before acting on any information in this article.
This piece was produced in association with London Pregnancy Clinic and Jeen Health, which provided background clinical information for editorial purposes.
Hyperlinks to external sources are included for reference only and do not represent an endorsement of any product, service or organisation.
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