When Your Body Is Doing “Too Much”: POTS, MCAS, and What It Might Mean for Your Fertility

If you have a body that seems to react to everything, crash for no obvious reason, or keep specialists stumped — and you’re also on an IVF journey — this one’s for you.

Let me start with something I hear a lot in my work with both my IVF and general clients: “I just feel like something is wrong with me, but no one can find it.”

The unexplained fatigue. The dizziness when you stand up. The way eating certain things sends your body into chaos. The sense that your nervous system is perpetually on high alert. The symptoms that seem unrelated — until, suddenly, they’re not.

Over the past few years, the research has started catching up to what many people with complicated, multisystem bodies have known for a long time: these things are often connected. And for people going through fertility treatment, that connection matters more than most of us have been told.

“The symptoms seem unrelated — until, suddenly, they’re not.”

Two conditions you may not have heard of — and why they matter

POTS stands for Postural Orthostatic Tachycardia Syndrome. It’s a disorder of the autonomic nervous system — the part of your nervous system that controls all the things you don’t consciously think about, like your heart rate, blood pressure, digestion, and temperature regulation. With POTS, when you stand up, your heart rate spikes in a way it shouldn’t, and your body struggles to regulate blood flow properly. The result can be dizziness, brain fog, exhaustion, nausea, and a whole-body feeling of just not coping.

MCAS stands for Mast Cell Activation Syndrome. Mast cells are immune cells whose job is to protect you from threats. In MCAS, those cells become overreactive, releasing inflammatory chemicals (including histamine) in response to things that shouldn’t trigger a reaction: certain foods, heat, stress, hormonal fluctuations, or sometimes nothing obvious at all. The result is a wide-ranging pattern of sensitivities and reactions that can be hard to pin down.

These two conditions very commonly occur together — often alongside a connective tissue condition called hypermobile Ehlers-Danlos Syndrome (hEDS) or Hypermobility Spectrum Disorder. Researchers have started calling this combination “the trifecta,” and studies now confirm that having one significantly increases the likelihood of having the others.1,2

They also disproportionately affect women of reproductive age. Which brings us to why I’m writing this.

What does this have to do with fertility?

Quite a lot, it turns out — though it’s still an emerging area of research, and there’s much more to learn.

Research suggests that women with POTS may have a higher rate of miscarriage than the general population, and a greater likelihood of gynaecological conditions like endometriosis and fibroids, which themselves affect fertility. On a more mechanical level, POTS can impair blood flow regulation throughout the body, including to the uterus — and adequate blood flow to the uterine lining is one of the key factors in whether an embryo successfully implants.3,4

MCAS tells a similar story from a different angle. Mast cells are present in the uterine lining, where they play a role in the immunological environment required for implantation. When those mast cells are overactive and releasing inflammatory signals at the wrong time, they may disrupt the carefully timed process of an embryo settling in and being accepted by the body.5

There is also a bidirectional relationship between histamine (the main chemical MCAS causes the body to overproduce) and oestrogen. Each one drives up the other. For people going through IVF, who are given high doses of oestrogen as part of stimulation, this feedback loop can become particularly significant — potentially worsening MCAS symptoms during treatment and affecting outcomes in ways that go unidentified.5

Patients with MCAS are sometimes labelled as “unexplained infertility” or “poor responders” in IVF. Without understanding what’s happening at the immune level, the underlying driver stays invisible.5

Patients with MCAS are sometimes labelled as “unexplained infertility” or “poor responders” in IVF. Without understanding what’s happening at the immune level, the underlying driver stays invisible.

There’s another piece to this puzzle: neurodivergence

This is where the research gets genuinely fascinating — and personally meaningful for a lot of the people I work with.

Studies have found substantial overlap between POTS, MCAS, and hypermobility on one hand, and Autism and ADHD on the other. A large Swedish population study found that people with EDS were 7.4 times more likely to be Autistic, and 5.6 times more likely to be ADHD, compared to matched controls. Elevated rates were also found in the unaffected siblings of people with EDS, suggesting this clustering has a genetic basis rather than simply being a response to living with a difficult illness.6

A UK study of over 100 neurodivergent adults (with diagnoses of autism, ADHD, and/or Tourette Syndrome) found that more than half showed signs of hypermobility, compared to about 20% in the general population. Critically, the study demonstrated that hypermobility appeared to explain why neurodivergent people are more prone to autonomic dysfunction and chronic pain — it was the statistical bridge between the two.7

In other words: if you’re Autistic and/or ADHD, your body is statistically more likely to also have a nervous system and immune system that work differently. And if you have POTS or MCAS, you’re statistically more likely to be neurodivergent — whether that’s been identified or not.

Research into the mast cell-autism connection adds another layer. Mast cells are found throughout the body, including in the brain, where their activation can trigger neuroinflammatory processes implicated in autism. Mast cell mediators like histamine and serotonin influence the very brain pathways that work differently in Autistic people. The stress-reactivity systems, the gut-brain axis, the immune environment — all of these overlap in ways researchers are only beginning to map.8,9

For ADHD specifically, research suggests that mast cell-driven neuroinflammation may disrupt the prefrontal dopamine and noradrenaline systems that govern attention and executive function — the same systems targeted by ADHD medication.10

In my work supporting clients, I see this convergence regularly: people who are neurodivergent, whose bodies also respond strongly to the hormonal and physical demands of IVF, whose symptoms have often been dismissed or fragmented across multiple specialists. The research is starting to explain what many have been living without language for.

What this might mean if you’re going through IVF

I want to be clear: this is not about adding to your list of worries. If you recognise yourself in any of this, it’s worth knowing about — not because it makes your journey harder, but because understanding what’s happening in your body can open up new conversations and, sometimes, new options.

Some things that may be worth exploring with your medical team:

•If you have unexplained infertility, repeated implantation failure, or have been told you’re a “poor responder,” asking about immune or autonomic factors may be worth raising.

•If your IVF cycles trigger significant physical deterioration — beyond typical side effects — POTS or MCAS may be part of the picture.

•If you’re Autistic and/or ADHD and haven’t been evaluated for hypermobility or dysautonomia, it may be worth looking into.

•Some fertility specialists and reproductive immunologists are beginning to incorporate MCAS management (including low-histamine approaches and mast cell stabilisers) around IVF cycles. This is an emerging area, and not all clinicians will be across it yet — but it’s a reasonable conversation to initiate.

It is also worth naming that many people with POTS and MCAS have had long, frustrating experiences of not being believed. If that’s been your story — years of being told your symptoms are anxiety, or that nothing shows up on tests — that history matters psychologically. The emotional weight of navigating IVF while also carrying an invisible, misunderstood illness is significant, and it deserves acknowledgment.

A note on this research

This is an evolving field. The links between POTS, MCAS, hypermobility, neurodivergence, and fertility outcomes are supported by growing peer-reviewed evidence, but we don’t yet have the large clinical trials that would translate this into standard fertility care. That’s part of why it matters to talk about it — awareness drives research, and research, eventually, changes practice.

The references underpinning this post are listed below. If you’d like to read the full research summary, it’s available on request.

About the author

Dr Liz Bancroft is a Clinical and Counselling Psychologist and EMDR-Accredited Practitioner based in South Perth, WA. She is the founder of Hope Affirm Thrive, Australia’s first neurodivergent-affirming psychological support program for IVF patients. Liz brings both professional and lived experience to her work in reproductive psychology.

To find out more about Hope Affirm Thrive or make an enquiry, visit www.hopeaffirmthrive.com.au www.bancroftpsychology.com

References

The following peer-reviewed studies and clinical sources informed this post.

1.Yao, J., et al. (2025). Association of postural orthostatic tachycardia syndrome, hypermobility spectrum disorders, and mast cell activation syndrome in young patients. Frontiers in Neurology. https://doi.org/10.3389/fneur.2025.1531234

2.Wang, M., et al. (2021). The relationship between mast cell activation syndrome, postural tachycardia syndrome, and Ehlers-Danlos syndrome. Annals of Allergy, Asthma & Immunology, 126(6), 593–595. https://doi.org/10.1016/j.anai.2021.01.016

3.Blitshteyn, S., Bett, G. L., & Poya, H. (2012). Pregnancy in postural tachycardia syndrome: Clinical course and maternal and fetal outcomes. Journal of Maternal-Fetal and Neonatal Medicine, 25(9), 1631–1634. https://doi.org/10.3109/14767058.2012.659410

4.Peggs, K. J., et al. (2012). Gynecologic disorders and menstrual cycle lightheadedness in postural tachycardia syndrome. International Journal of Gynaecology and Obstetrics, 118(3), 242–246. https://doi.org/10.1016/j.ijgo.2012.04.014

5.University Reproductive Associates. (n.d.). The link between mast cell activation syndrome (MCAS) and infertility. https://uranj.com/blogs/b51.php

6.Ced erlöf, M., et al. (2016). Nationwide population-based cohort study of psychiatric disorders in individuals with Ehlers-Danlos syndrome or hypermobility syndrome and their siblings. BMC Psychiatry, 16, 207. https://doi.org/10.1186/s12888-016-0922-6

7.Csecs, J. L. L., et al. (2022). Joint hypermobility links neurodivergence to dysautonomia and pain. Frontiers in Psychiatry, 12, 786916. https://doi.org/10.3389/fpsyt.2021.786916

8.Otądżka, A., et al. (2024). Mast cells in autism spectrum disorder — The enigma to be solved? International Journal of Molecular Sciences, 25(5), 2651. https://doi.org/10.3390/ijms25052651

9.Theoharides, T. C., et al. (2024). Mast cells in the autonomic nervous system and potential role in disorders with neuropsychiatric manifestations. Annals of Allergy, Asthma & Immunology, 132(4), 440–454. https://doi.org/10.1016/j.anai.2023.10.007

10.Song, Y., et al. (2020). Mast cell mediated neuroinflammation may have a role in attention deficit hyperactivity disorder. Experimental and Therapeutic Medicine, 20(2), 714–726. https://doi.org/10.3892/etm.2020.8763

This post is for informational purposes and does not constitute medical advice. Please consult your treating team before making any changes to your care.