October 15 is Pregnancy and Infant Loss Awareness Day—a date that holds profound meaning for the millions of families who have experienced miscarriage, stillbirth, or the death of a newborn. Across the full month of October, Pregnancy and Infant Loss Awareness Month creates space for remembrance, community, and a kind of education that is rarely offered clearly: what can we actually understand about the biology of loss, and what does that mean for those who want to try again?
This article is written with deep respect for that grief. There are no simple answers, and no test that explains everything—or that removes the weight of loss. What there is, for those who are ready, is a framework: a way of understanding the biomarker categories that clinicians use when evaluating pregnancy loss, so that conversations with healthcare providers can be better informed, more directed, and less overwhelming.
If you are not yet ready for this kind of information, that is completely valid. When you are, it will be here.
What Pregnancy and Infant Loss Awareness Month Means
Honouring Loss and Reducing Stigma
Pregnancy and infant loss is far more common than public conversation reflects. Miscarriage alone affects an estimated 10–20% of known pregnancies—and likely more, as many early losses occur before a pregnancy is confirmed. Stillbirth affects approximately 1 in 160 pregnancies in the United States. Neonatal death, the loss of a baby within the first 28 days of life, touches thousands of families each year.
Despite this prevalence, loss remains surrounded by silence. Many people carry their grief privately, unsure whether to speak about a pregnancy that others may not have known existed. Many feel—incorrectly—that something they did or did not do contributed to their loss. The first and most important thing this awareness month affirms is this: pregnancy loss is not a personal failing. It is a medical event, most often with biological causes that no individual could have prevented or foreseen.
Why Education and Support Matter
Awareness months serve a dual purpose: they create cultural space for acknowledgment, and they improve the quality of information available to those navigating difficult experiences. For pregnancy and infant loss, education matters in a specific and practical way: many people who experience loss—particularly recurrent loss—want to understand what happened and what they can do. Clear, compassionate information about evaluation pathways and biomarker categories is one meaningful contribution to that understanding.
It is equally important to acknowledge the disparities that shape who experiences pregnancy loss and who receives adequate support. Non-Hispanic Black and Indigenous communities in the United States face disproportionately higher rates of stillbirth and neonatal mortality, driven in large part by structural inequities in healthcare access, systemic bias in clinical care, and the compounding effects of chronic stress. Awareness without equity is incomplete—and any conversation about reproductive health must hold this reality.
Understanding Types of Pregnancy and Infant Loss
Miscarriage, Stillbirth, and Neonatal Loss
Clinically, pregnancy and infant loss is categorised by the timing and circumstances of the loss, and these distinctions carry meaning for evaluation pathways.
Miscarriage is the loss of a pregnancy before 20 weeks of gestation. The majority of miscarriages—estimated at 50–70%—are attributable to chromosomal abnormalities in the embryo, a biological event that occurs at the moment of fertilisation and is not influenced by anything the pregnant person does or does not do. Other causes include uterine structural issues, hormonal factors, infections, clotting conditions, and immune dysfunction.
Stillbirth is the loss of a baby at or after 20 weeks of gestation. Stillbirth has a broader range of causes that can include placental dysfunction, umbilical cord complications, infections, chromosomal abnormalities, and maternal medical conditions including hypertension and diabetes. In a significant proportion of cases—approximately one-third—no definitive cause is identified even after thorough evaluation.
Neonatal death refers to the death of a live-born infant within the first 28 days of life, and is often associated with prematurity, congenital abnormalities, infection, or complications of labour and delivery. Each of these losses is distinct in its biology, its timing, and its emotional weight—and each may involve different evaluation considerations for future pregnancies.
What “Recurrent Pregnancy Loss” Means
Recurrent pregnancy loss (RPL) is defined clinically as two or more pregnancy losses, though some specialist guidelines support evaluation after a first loss depending on clinical circumstances and individual history. RPL affects approximately 1–2% of couples trying to conceive, and it is the subset of loss for which the most structured biomarker evaluation pathways exist.
For individuals with recurrent loss, evaluation typically spans multiple categories: chromosomal, anatomical, hormonal, metabolic, inflammatory, and clotting or immune. This comprehensive approach reflects the reality that RPL is rarely caused by a single factor, and that identifying a contributing factor—even when it cannot explain every loss—can meaningfully shape the clinical management of a subsequent pregnancy.
Why Loss Can Happen: A High-Level Clinical View
Early vs Late Loss Pathways
The biology of pregnancy loss differs significantly depending on when it occurs. Early losses—in the first trimester—are most commonly associated with chromosomal abnormalities in the embryo, often random events that are unlikely to recur. They can also involve implantation failure, progesterone insufficiency, thyroid dysfunction, or immune factors that disrupt the early maternal-embryonic relationship.
Later losses—in the second trimester or at term—more often involve placental dysfunction, uterine abnormalities, cervical insufficiency, maternal medical conditions, or infections. The placenta, which develops and matures across pregnancy, plays a central role in sustaining fetal growth and wellbeing; disruptions in placental function can lead to growth restriction, preterm birth, or stillbirth.
Understanding this distinction matters for evaluation: the biomarker categories most relevant to first-trimester recurrent loss differ from those most relevant to late pregnancy complications, and a comprehensive clinical workup accounts for both.
Modifiable Risk Factors vs Non-Modifiable Factors
Not all contributors to pregnancy loss are modifiable—and that distinction carries enormous emotional significance. Chromosomal abnormalities, for example, are not preventable; they reflect the inherent biological imprecision of cell division. Most structural uterine abnormalities are not a result of anything a person did.
What biomarker evaluation can identify are the modifiable contributors: thyroid dysfunction that can be treated, metabolic imbalances that can be addressed before conception, inflammatory states that can be monitored, and clotting conditions that can be managed with specialist-guided anticoagulation during pregnancy. The value of this identification is not to assign blame for past losses—it is to inform proactive steps for future pregnancies.
Key Biomarker Categories That Add Context
The biomarkers discussed in this section are those commonly included in clinical workups for preconception planning and recurrent pregnancy loss evaluation. None of them provides a complete answer on its own, and none can definitively explain any individual loss. What they offer, in context, is a more complete biological picture—one that supports better clinical conversations and more tailored care.
Thyroid Function and Thyroid Antibodies (TSH, Free T4, TPO)
Thyroid function is one of the most well-established modifiable contributors to pregnancy outcomes. The thyroid gland regulates metabolism, hormonal balance, and—critically during pregnancy—fetal neurological development. Both underactive thyroid (hypothyroidism) and overactive thyroid (hyperthyroidism) are associated with increased risks of miscarriage, preterm birth, and pregnancy complications.
TSH (thyroid-stimulating hormone) is the primary screening marker for thyroid function. A TSH outside the trimester-specific reference range for pregnancy—which is narrower than the standard adult range—may indicate thyroid dysfunction that warrants further evaluation and, when indicated, treatment. Free T4 measures the active thyroid hormone circulating in the bloodstream and provides additional context when TSH is borderline or abnormal.
Thyroid peroxidase antibodies (TPO antibodies) measure the presence of autoimmune activity targeting the thyroid gland—a pattern associated with Hashimoto’s thyroiditis. Even when thyroid function tests are within normal range, elevated TPO antibodies have been associated in research with higher rates of miscarriage in some studies, leading many reproductive endocrinologists to include TPO testing as part of recurrent pregnancy loss evaluation.
Thyroid dysfunction is among the most treatable contributors to reproductive risk—which is precisely why thyroid screening is consistently recommended in preconception planning.
Reproductive Hormones (Progesterone and Quantitative β-hCG Trends)
In the very early weeks of pregnancy, two hormones provide critical information about how a pregnancy is developing: progesterone and quantitative β-hCG.
Progesterone is essential for preparing the uterine lining to receive and maintain a pregnancy. In early pregnancy, it is initially produced by the corpus luteum—the structure that remains in the ovary after ovulation—and later by the placenta. Low progesterone in early pregnancy has been associated with pregnancy loss, though the relationship is complex: low progesterone may sometimes reflect a struggling pregnancy rather than cause one. Serial progesterone measurements, interpreted alongside clinical findings, provide more useful information than any single result.
Quantitative β-hCG (beta-human chorionic gonadotropin) is the hormone produced by the developing placenta and the basis of pregnancy tests. In a healthy early pregnancy, β-hCG typically doubles approximately every 48–72 hours in the early weeks. A β-hCG that rises more slowly, plateaus, or falls may indicate an early pregnancy that is not progressing—though interpretation always requires clinical context, including gestational age and ultrasound findings. Serial β-hCG levels are one of the most informative tools available in early pregnancy monitoring precisely because the trend matters far more than any single measurement.
LH (luteinising hormone) and FSH (follicle-stimulating hormone) are also relevant in the preconception context, where they provide information about ovarian reserve and cycle regulation—factors that can influence both the ability to conceive and early pregnancy stability.
Metabolic Health (Fasting Glucose, HbA1c, Lipids)
Metabolic health before and during pregnancy has meaningful implications for pregnancy outcomes. Poorly controlled blood sugar—particularly insulin resistance and undiagnosed type 2 diabetes—is associated with elevated risk of miscarriage, stillbirth, and neonatal complications.
Fasting glucose and HbA1c (glycated haemoglobin, which reflects average blood sugar over the preceding two to three months) are two foundational markers for assessing glucose metabolism before conception. HbA1c is particularly useful in preconception planning because it provides a longer-term picture of glucose control that a single fasting measurement cannot capture. An HbA1c within a healthy range before conception is associated with meaningfully reduced pregnancy complication risk in individuals with diabetes or prediabetes.
A lipid panel—measuring total cholesterol, LDL, HDL, and triglycerides—provides additional context for cardiometabolic health. Dyslipidaemia is associated with endothelial dysfunction and inflammatory states that can affect placental development and pregnancy maintenance. Addressing lipid imbalances before conception, where appropriate, is a component of comprehensive preconception care.
Inflammation (CRP)
C-reactive protein (CRP) is a marker of systemic inflammation produced by the liver in response to inflammatory signals. Chronic low-grade inflammation is associated with a range of adverse pregnancy outcomes, including implantation failure, miscarriage, and complications of later pregnancy.
CRP does not pinpoint the source of inflammation—it is a non-specific marker that rises in response to many inflammatory triggers, including infection, autoimmune activity, metabolic dysfunction, and lifestyle factors. What it offers is a window into the overall inflammatory environment of the body at the time of testing.
In preconception planning, establishing a CRP baseline can help identify whether chronic inflammation is a factor worth addressing before pregnancy. Tracking CRP over time—particularly in the context of lifestyle modifications aimed at reducing inflammatory burden—provides feedback that is both clinically informative and personally meaningful.
Clotting and Immune Markers (Antiphospholipid and Thrombophilia Panels)
Among the most clinically significant contributors to recurrent pregnancy loss are clotting and immune conditions—specifically antiphospholipid syndrome (APS) and inherited thrombophilias.
Antiphospholipid syndrome is an autoimmune condition in which the body produces antibodies that increase the tendency of blood to clot. In pregnancy, APS is associated with recurrent miscarriage, stillbirth, and severe pre-eclampsia, primarily through its effects on placental blood flow. The antibodies central to APS evaluation include lupus anticoagulant, anticardiolipin antibodies, and anti-beta-2 glycoprotein I (anti-β2GPI) antibodies. Because these antibodies can fluctuate, their clinical significance requires confirmation of positive results on two occasions at least 12 weeks apart—underscoring the importance of specialist interpretation rather than single-point consumer testing.
Inherited thrombophilias are genetic conditions that increase clotting tendency and are assessed through markers including protein C, protein S, factor V Leiden, and prothrombin gene mutation (factor II). The clinical significance of these conditions in pregnancy loss remains an area of active research, and treatment decisions—including whether to use anticoagulants during pregnancy—require careful specialist evaluation.
ANA (antinuclear antibody) testing may also be included as a broader autoimmune screen, providing context for whether underlying connective tissue disease may be contributing to pregnancy complications.
These markers are included here to support biomarker literacy—so that individuals encountering these terms in clinical conversations are better prepared to engage meaningfully with their care team.
Emerging Placental Protein Markers (PAPP-A, sFlt-1, PlGF)
Placental biomarkers represent a frontier area of prenatal medicine, particularly for identifying pregnancies at elevated risk for complications in the second and third trimesters.
PAPP-A (pregnancy-associated plasma protein A) is measured as part of first-trimester combined screening and reflects placental development in early pregnancy. Low PAPP-A in the first trimester has been associated with increased risk of stillbirth, preterm birth, and growth restriction later in pregnancy.
sFlt-1 (soluble FMS-like tyrosine kinase-1) and PlGF (placental growth factor) are markers of placental angiogenesis—the process by which the placenta develops its blood vessel network. The sFlt-1:PlGF ratio is used in some clinical settings to assess risk of pre-eclampsia and to support monitoring in high-risk pregnancies. An elevated ratio may indicate placental dysfunction before symptoms become clinically apparent.
These markers are used in clinical and research settings and are mentioned here as educational context—to illustrate how placental biomarker science is evolving, and how future conversations with maternal-fetal medicine specialists may incorporate this level of biological detail.
What Lab Testing Can—and Cannot—Tell You
Patterns, Not Proof
No biomarker result—individually or collectively—can definitively explain why a pregnancy was lost. This is one of the most important things to understand about laboratory evaluation in the context of pregnancy loss: it offers patterns, context, and probability—not certainty, causation, or blame.
A positive antiphospholipid antibody does not mean it caused your loss. A normal thyroid panel does not mean thyroid function played no role. A suboptimal HbA1c does not mean you failed your pregnancy. What these results can do is inform the clinical approach to a future pregnancy—guiding monitoring protocols, specialist referrals, and targeted interventions that may reduce risk going forward.
Approaching biomarker results with this framing—as data that informs, not verdicts that conclude—is both scientifically accurate and emotionally protective.
When Specialist Referral Is Appropriate
For individuals with two or more pregnancy losses, evaluation with a reproductive endocrinologist (REI), maternal-fetal medicine (MFM) specialist, or rheumatologist—depending on which biomarker categories are most relevant—is a well-supported clinical pathway. Many of the markers described in this article, particularly those in the antiphospholipid and thrombophilia categories, should be ordered, interpreted, and acted upon under specialist guidance.
A general practitioner or OB-GYN is often the appropriate starting point for initiating the conversation about evaluation—and for ordering baseline thyroid, metabolic, and inflammatory markers. For more complex evaluations involving clotting and immune panels, specialist collaboration is important both for accurate interpretation and for ensuring that any treatment decisions are made with appropriate expertise.
Taking Ownership of Reproductive Health Data
Preconception “Baseline” Testing
For individuals who have experienced loss and are considering a future pregnancy, building a preconception biomarker baseline is a practical and empowering step. A foundational baseline might include a thyroid panel (TSH, free T4, TPO antibodies), a metabolic panel (fasting glucose, HbA1c, lipids), an inflammatory marker (CRP), and a complete blood count (CBC)—which can flag anaemia, iron status, or platelet abnormalities relevant to both fertility and pregnancy.
This baseline does not constitute a comprehensive RPL workup—it is a starting point that can identify common modifiable contributors and generate targeted questions for clinical conversations. For those with specific risk factors or a history of multiple losses, this baseline should be expanded in consultation with a healthcare provider.
Timing matters for preconception testing: ideally, baseline markers are assessed before conception, allowing time for any abnormalities to be addressed without the urgency of an active pregnancy. Three to six months before planned conception is a reasonable window for most preconception evaluation.
Tracking Trends Across Time and Pregnancies
One of the most valuable shifts in thinking about biomarker data is the move from single-point measurement to trend interpretation. A single CRP value is a snapshot; a series of values tracked over months—particularly in the context of lifestyle changes, treatment adjustments, or pregnancy—tells a more meaningful story.
For individuals in early pregnancy who are being monitored with serial β-hCG and progesterone, understanding that the trend is the message—not any single number—can reduce the anxiety that often accompanies early pregnancy monitoring. These trends, reviewed with a clinician, provide the clearest available picture of early pregnancy trajectory.
Preparing for More Informed Conversations and Support
Arriving at a clinical appointment with some biomarker literacy changes the nature of the conversation. It allows you to ask more specific questions: “Should we test my thyroid antibodies given my history?” “What would serial progesterone monitoring look like in a future pregnancy?” “Is an antiphospholipid panel appropriate given I’ve had two losses?” These questions position you as an engaged participant in your own care—which is both your right and one of the most effective tools available.
Beyond lab testing, it is essential to acknowledge the emotional dimensions of navigating pregnancy after loss. Anxiety, grief, hypervigilance, and PTSD symptoms are recognised psychological responses to pregnancy loss—and they are real, valid, and deserving of dedicated support. Mental health resources specific to pregnancy loss, peer support communities, and grief counselling are part of comprehensive care, not an afterthought. Bringing your whole experience—not just your lab results—to your healthcare conversations is equally important.
Closing: Remembrance and Agency Together
October 15 is the night of the Wave of Light—when families around the world light candles at 7:00 PM in their local time zones, creating a continuous wave of illumination in honour of babies lost too soon. It is a moment of collective grief and profound solidarity.
This awareness month holds space for that grief. It also makes room for something else: the quiet determination of those who want to understand, to prepare, and to try again. These are not competing impulses. They are two expressions of the same love.
If you are at a point where biomarker education feels relevant and useful, the categories described in this article are a starting point—not an answer, but a better set of questions to bring to the people who can help you find your path forward. Your history deserves to be understood as fully as possible. Your future pregnancy deserves every advantage that informed, compassionate clinical care can offer.
You deserve both.
This article is for educational purposes only and does not constitute medical advice or replace the guidance of a licensed healthcare professional. Biomarkers provide supportive context for clinical conversations—they do not diagnose conditions, explain individual losses definitively, or predict outcomes. All evaluation and treatment decisions should be made in partnership with qualified healthcare providers, including OB-GYN, reproductive endocrinology, maternal-fetal medicine, and mental health specialists as appropriate. If you are in grief, please reach out to a pregnancy loss support organisation or mental health professional.
