A Quieter Piece of the Recurrent Pregnancy Loss Puzzle: What Metabolic Health May Be Telling Us

If you've experienced recurrent pregnancy loss, you already know how heavy the silence can feel. The testing comes back unremarkable, the appointments end with shrugs, and somehow you're left to make sense of it on your own. You are not alone in this, and you are not without options.

About half of recurrent pregnancy loss cases are labeled "unexplained," meaning standard workups don't reveal a clear cause. But unexplained doesn't mean unaddressable. Research is increasingly pointing toward metabolic health, particularly insulin resistance, as a quiet contributor that often gets missed on routine fertility panels. A new study published in 2026 offers some very practical insight, and one predictive marker for pregnancy loss in particular stood out.

Meet METS-IR

METS-IR stands for Metabolic Score for Insulin Resistance. It's calculated using values most people already have in their bloodwork: fasting glucose, triglycerides, HDL cholesterol, and BMI. No new tests, no specialty labs, just a more meaningful way of looking at numbers that may already be sitting in your file.

In the study mentioned above, which followed nearly 900 women with a history of two or more pregnancy losses, METS-IR was the strongest predictor of who went on to experience another loss versus who carried to term. Women with the highest METS-IR scores had roughly a 49% higher likelihood of pregnancy loss compared to those with lower scores.

That's a meaningful signal, and it's worth understanding why.

Why This Marker Catches What Others Usually Miss

Most fertility workups don't include a specific look at insulin resistance unless something obvious flags it, like a PCOS diagnosis or elevated fasting glucose. The trouble is, insulin resistance often develops quietly, long before blood sugar starts to rise. You can feel completely fine and still have a body that's working harder than it should to keep things in balance.

What makes METS-IR useful is that it pulls together several pieces of metabolic information at once. Glucose, lipids, and body composition all tell part of the story, and looking at them together gives a fuller picture than any single number could. It picks up on the kind of subtle metabolic patterns that often get overlooked in standard reproductive testing.

How Insulin Resistance May Affect Pregnancy

When the body becomes less responsive to insulin, the ripple effects reach further than blood sugar. Research suggests insulin resistance may influence:

• The receptivity of the uterine lining, which plays a key role in whether an embryo successfully implants and continues to develop.

• The inflammatory environment at the maternal-fetal interface, which needs to stay carefully balanced to support a pregnancy.

• Hormonal signalling that supports ovulation, implantation, and early pregnancy. Egg quality, which is shaped over the months leading up to ovulation.

  
  

None of this means insulin resistance causes pregnancy loss directly, but it can quietly shift the conditions in ways that make pregnancy harder to sustain.

One Important Marker, But Not the Whole Story

Here's where I want to be careful. METS-IR is a useful tool, but it's a single piece of a much larger picture. It's a screening signal, not a diagnosis, and it certainly isn't a verdict on your fertility.

A truly thorough assessment looks at many layers together, including thyroid function, nutrient status (think vitamin D, B12, iron, and others), inflammation, autoimmune markers, hormonal balance across the cycle, gut health, sleep quality, stress patterns, clotting disorders and lifestyle context. Insulin resistance can play a role, sometimes a significant one, but it rarely acts alone. Pregnancy loss is almost always multifactorial, and the most useful approach is one that respects that complexity rather than reducing it to any single number.

What METS-IR does offer is a starting point. A way to ask better questions, identify patterns that may have been missed, and bring something concrete to the conversation with your care team.

Why the Preconception Window is Critical

One of the most hopeful aspects of this research is its focus on the months before pregnancy begins. The body responds to changes made during this window, and metabolic health in particular is responsive to personalized, precise and sustained support.

This is often the time that feels the most uncertain after a loss. The waiting, the not knowing, the wondering whether to try again. Reframing it as preparation rather than limbo can shift the experience. It's a chance to gather information, build a stronger foundation, and walk into your next pregnancy feeling more supported than the last.

What You Can Take Away

If something in this piece resonates, here are a few thoughts to sit with:

• Metabolic health deserves attention in any recurrent pregnancy loss workup, even when no obvious metabolic condition has been diagnosed.

• Routine bloodwork can offer more than it's often given credit for when interpreted through the right lens.

• The preconception period is a meaningful window, not just a waiting room. And you have far more agency in this process than you may have been led to believe.

A Note Before You Go

Everything shared here is educational, not medical advice. Your situation is uniquely yours, and the right next steps depend on your full history, your goals, and the guidance of the team caring for you. Please keep working closely with your Naturopathic Doctor and care team overall, and feel welcome to bring any of this into that conversation if it feels relevant.

If you'd like a more personalized look at how metabolic health, nutrition, lifestyle, and other modifiable factors may be playing a role in your fertility journey, we are here to support you.

Booking a consultation is a chance to review your individual picture, explore strategies that fit your life, and work alongside your existing care team to build something that feels both grounded and hopeful.

Wherever you are in this, we are here to support you in navigating the next steps.