Placental problems, fetal conditions, maternal illness, infection, and sudden interruptions in umbilical blood flow can all lead to stillbirth. Several factors may act together, such as placental insufficiency combined with high blood pressure. No single cause explains every fetal death, and some remain unexplained after a careful clinical review.
This clinical overview covers stillbirth causes, risk factors, warning signs, prenatal care, evaluation, recovery, and planning after pregnancy loss, with practical guidance for pregnant people and families.
Stillbirth and Its Many Possible Causes
Stillbirth is the death of a fetus at or after 20 completed weeks of pregnancy. It differs from an early pregnancy loss before that point and neonatal death after birth. Definitions and reporting rules vary by location, so your care team applies the standards used where you received care.
That distinction matters because fetal death can develop through several mechanisms. Oxygen may fail to reach the fetus, blood flow through the placenta or umbilical cord may stop, severe illness may overwhelm the pregnancy, or a serious fetal condition may disrupt development.
The Major Contributing Categories
Placental dysfunction is among the most frequent findings. The placenta may not deliver oxygen and nutrients efficiently, may separate before delivery, or may become inflamed. Fetal growth restriction, also called intrauterine growth restriction, can reflect reduced placental support, although restricted growth can have other causes.
- Placental problems: Poor blood flow, premature separation, or inflammation may reduce the oxygen reaching the fetus.
- Fetal conditions: Chromosomal abnormalities, congenital anomalies, or severe growth problems may affect survival.
- Maternal health conditions: High blood pressure, preeclampsia, diabetes, obesity, and clotting disorders can raise risk.
- Infection: Certain infections during pregnancy can cross the placenta and seriously affect fetal development.
- Cord complications: A sudden loss of blood or oxygen through the umbilical cord can cause fetal death.
Unexplained stillbirth means that a thorough evaluation did not identify a clear cause. It does not mean the loss was imagined or that someone overlooked an obvious problem. Placental examination, medical history, laboratory analysis, and fetal assessment may still leave questions because some deaths lack a single visible trigger.
Placental, Fetal, and Cord Complications
Placental, fetal, or cord findings can clarify what happened even when a review identifies no single trigger. Reduced oxygen delivery is one pathway, but it may develop gradually or begin with a sudden interruption in blood flow.
A placenta that supplies less oxygen resembles a river whose flow has slowed: blood may still reach the fetus, but not consistently enough to support growth. Placental insufficiency is this inadequate supply, and it may be linked to maternal blood vessel disease, hypertension, smoking, or other pregnancy complications.
Impaired Blood Flow and Premature Separation
Placental abruption occurs when the placenta separates from the uterine wall before delivery. It can result from high blood pressure, trauma, blood-clotting problems, or an unclear trigger. Bleeding may be visible, concealed, or very light, even when the separation is serious.
Fetal growth measurements offer another view of placental function. A fetus that isn’t gaining weight as expected may be receiving inadequate oxygen or nutrients. Your maternity care professional may repeat measurements, review umbilical cord blood flow, or schedule closer surveillance because one small measurement doesn’t provide the full picture.
Cord Accidents and Fetal Conditions
Most umbilical cord accidents do not cause harm. Fetal movement and blood flow normally change the cord’s shape and position. A true accident involves a sudden event that seriously interrupts blood flow, such as a knot tightened enough to block circulation or a cord segment trapped during delivery.
| Finding | What it means | Connection to fetal death |
|---|---|---|
| Placental insufficiency | The placenta does not reliably meet pregnancy needs | Low oxygen or nutrients may cause growth restriction or fetal death |
| Placental abruption | The placenta separates before delivery | The fetus may lose its oxygen supply |
| Severe cord obstruction | Blood flow falls suddenly or completely | Oxygen delivery can stop |
| Major fetal anomaly | A structural or genetic condition disrupts development | Some conditions are incompatible with survival |
Less frequent causes include major congenital anomalies and chromosomal abnormalities. Severe fetal hydrops, a buildup of fluid caused by heart failure or another problem, can place enough strain on a pregnancy to end in fetal death. Evaluation may include detailed ultrasound, fetal heart assessment, genetic examinations, and placental examination after delivery.
Maternal Conditions and Infections That Raise Risk
A sudden cord obstruction can interrupt oxygen delivery within minutes, while a maternal condition may reduce fetal support over time. Because these mechanisms differ, your clinician considers symptoms, prenatal findings, and the course of the pregnancy rather than relying on one risk factor.
Placental blood vessels depend on the mother’s circulation. Conditions that damage those vessels or alter maternal metabolism can deprive the fetus of adequate support. This does not mean every pregnancy affected by one of these conditions ends in loss; closer monitoring may be needed.
Health Conditions That Affect Blood Flow
Chronic hypertension raises the risk of placental abruption, preeclampsia, and fetal growth restriction. Preeclampsia combines abnormal blood pressure with findings such as protein in the urine or impaired organ function. Severe forms can reduce placental function and require urgent specialist care.
Diabetes outside its target range can affect fetal growth and blood flow. Obesity is also associated with hypertension, preeclampsia, blood-clotting problems, and placental dysfunction. Certain inherited or acquired blood-clotting disorders may raise the risk of placental separation. One of these factors does not establish what caused a particular stillbirth.
- Poor fetal growth: An estimated fetal weight below the expected range may prompt closer evaluation.
- Multiple pregnancy: Carrying twins or more than two fetuses places greater demands on the placenta.
- Smoking: Cigarette smoking is linked to placental problems, restricted growth, and fetal death.
- Advanced maternal age: Risk rises gradually with age, though most pregnancies at older ages have healthy outcomes.
- Preeclampsia or hypertension: These conditions can restrict blood flow and reduce oxygen delivery.
Infections During Pregnancy
Listeriosis and parvovirus B19 are examples of infections that can affect a fetus. Foodborne listeria may cause miscarriage, fetal death, or newborn illness. Parvovirus B19 can stop red blood cell production, leading to severe fetal anemia, although many exposed pregnancies continue without harm.
These infections do not account for most stillbirths. Other infections may matter based on symptoms, travel, or exposure history, so tell your care team about relevant events rather than assuming every fever caused the outcome. The Centers for Disease Control and Prevention provides pregnancy-specific guidance on food safety, handwashing, and vaccines.
Pregnancy-specific prevention guidance helps reduce infection risk, but warning signs still require immediate medical attention.
Changes That Need Prompt Medical Attention
Reduced placental support may first appear as slower growth, but a change in movement can signal a more urgent problem. Babies move throughout the day and night, so no single pattern fits every pregnancy. A clear reduction in your baby’s usual movement deserves prompt contact with your maternity care professional.
Movement and Routine Monitoring
Prenatal visits can track blood pressure, maternal symptoms, fundal height, fetal growth, and the fetal heart rate. These checks may identify concerning patterns, but no monitoring system detects every complication. A reassuring visit does not remove the need to report a later change in movement.
Do not wait for the next appointment or rely on a home Doppler device to judge the situation. After movement slows or stops, contact the maternity unit, labor and delivery unit, or maternity triage service where you receive care. The team may check the fetal heartbeat, review symptoms, and decide whether further evaluation is needed.
Contact your maternity care service promptly for new or marked fetal movement changes, vaginal bleeding, severe abdominal pain, leaking fluid, contractions, fever, or a severe headache with vision changes.
Symptoms That Need Prompt Evaluation
Reduced movement is only one warning sign. Bleeding may come from the cervix, placenta, or another source. Abdominal pain can occur with abruption, preeclampsia, or less urgent conditions. Fluid leakage may reflect ruptured membranes, while a severe headache or visual changes may signal a hypertensive emergency.
Seek urgent maternity evaluation for a major change in the baby’s movement pattern, heavy or unexplained bleeding, severe or persistent pain, fluid leaving the vagina, or feeling seriously unwell. Use the local emergency number for severe symptoms or when you cannot reach the maternity service. Your team needs to evaluate both you and the pregnancy.
Prompt assessment addresses urgent problems first, while ongoing prenatal care can reduce risks before complications become serious.
Reducing Risk Through Prenatal Care and Medical Management
Prenatal care cannot remove every cause of fetal death, but it can identify several problems before they become severe. Its main advantage is repeated evaluation. Blood pressure, growth, laboratory results, and fetal patterns can change over time, so one normal visit offers only a single piece of information.
Practices That Address Specific Risks
- Attend prenatal visits: These visits track maternal health, fetal growth, and findings that may need closer evaluation.
- Monitor blood pressure: High readings may signal hypertension or preeclampsia even before other symptoms appear.
- Follow blood-glucose plans: Your maternity team can adjust diabetes care around pregnancy, meals, activity, and medicine.
- Avoid smoking: Stopping at any point removes exposure and supports placental function.
- Practice food safety: Cook animal products thoroughly, refrigerate perishable food, and avoid unpasteurized products.
- Review medicine use: Ask your clinician about prescriptions, over-the-counter products, vitamins, supplements, and herbal products.
These steps address selected risks, not every possible outcome. Advanced maternal age, a prior stillbirth, congenital anomalies, and unexplained fetal death cannot all be changed. Age alone also does not mean pregnancy loss is inevitable. Your clinician weighs it alongside your medical history and current findings.
Growth Assessments and Specialist Care
Your maternity care professional may order repeated growth measurements or ultrasound studies when growth appears slow. Maternal-fetal medicine specialists, also called high-risk pregnancy specialists, become involved with complex medical conditions or uncertain fetal findings. They estimate risks, coordinate surveillance, and plan care based on your circumstances.
Sleep position alone has not been established as a direct cause of stillbirth. Some research links certain sleep patterns with risk, but its findings do not show that one sleeping position causes fetal death. Follow your maternity team’s sleep guidance, and report stressful situations or mental health concerns. Severe or persistent stress deserves support, but routine family stress and everyday emotion have not been shown to explain most stillbirths.
Evaluation, Support, and Planning a Future Pregnancy
Growth restriction identified during pregnancy may lead to closer surveillance before a pregnancy is lost, while an unexpected loss requires a careful review afterward. That review may explain one part of what happened without resolving every question.
Unresolved details affect emotional recovery and decisions about a future pregnancy. A clear diagnosis is helpful, but unexplained stillbirth does not mean medical care is unavailable. Your care should address both the clinical record and the support you need during recovery.
What the Clinical Review May Include
Your clinician may review the pregnancy history, reported symptoms, prenatal records, laboratory results, delivery records, and medical conditions. Examination of the placenta can reveal bleeding, inflammation, blood-flow patterns, or other abnormalities. Genetic assessment may be offered because chromosome conditions and other inherited issues can contribute to fetal death.
Placental pathology provides tissue findings, but it cannot always identify the process that began it. An infection may leave signs even after it is no longer detectable. Cord and fetal findings can support an evaluation, yet unexpected fetal death sometimes leaves no decisive clue. The result should form part of your medical record whether it identifies a cause or remains unexplained.
Counseling and Future Pregnancy Care
A maternal-fetal medicine specialist or genetics professional can review the evidence, estimate recurrence risk, and outline tests or surveillance for a later pregnancy. Clinical guidance on pregnancy evaluation and care is available from the American College of Obstetricians and Gynecologists, commonly called ACOG. Its recommendations fit within a plan shaped by your history and current health.
Emotional support should accompany medical care after pregnancy loss. Your maternity unit, hospital, or community health service may connect you with a bereavement counselor, support group, or specialist trained in pregnancy loss. Such support can help with grief, anxiety, uncertainty, and decisions made at your own pace without imposing a deadline.
A previous stillbirth does not mean a later pregnancy will have the same outcome. The next plan differs according to whether placental insufficiency, hypertension, infection, a genetic condition, or unexplained loss was identified. You deserve a clear account of what is known, what remains uncertain, and which findings may shape your next pregnancy.
Bottom Line
Fetal death usually results from an interaction among placental, fetal, cord, infectious, or maternal factors, and many cases remain unexplained. Prenatal care, avoiding smoking, managing health conditions, and responding quickly to movement changes can reduce selected risks. After a loss, individualized clinical review and compassionate support can guide recovery and any future pregnancy.
FAQ
What is the medical definition of stillbirth?
Stillbirth is the death of a fetus at or after 20 completed weeks of pregnancy. It differs from early pregnancy loss before 20 weeks and neonatal death after birth. Definitions may vary by country or healthcare system.
What are the most common causes of stillbirth?
Placental dysfunction is a leading contributor. Other causes include umbilical cord accidents, fetal growth restriction, chromosomal abnormalities, congenital anomalies, maternal conditions such as preeclampsia, severe infection, and sudden pregnancy complications. No single cause applies to every stillbirth.
How often is the cause of a stillbirth unknown?
A substantial number of stillbirths remain unexplained after evaluation. The proportion varies by population, clinical setting, and the depth of testing. Unexplained stillbirth means no clear cause was identified; it does not mean the loss was imagined or that an obvious problem was overlooked.
Which maternal, fetal, and placental conditions increase the risk?
Risk increases with placental insufficiency, fetal growth restriction, preeclampsia, severe hypertension, diabetes outside its target range, obesity, certain clotting disorders, congenital anomalies, and chromosomal abnormalities. A risk factor increases likelihood within a group but does not predict one person’s outcome.
Can lifestyle factors such as smoking increase the risk?
Yes. Smoking is linked to placental problems, fetal growth restriction, and fetal death. Stopping at any point removes exposure and supports placental function, although it cannot reverse every complication that has already developed.
What risk factors increase the chance of stillbirth?
Placental insufficiency, fetal growth restriction, smoking, obesity, preeclampsia, poorly controlled diabetes, multiple pregnancy, some blood-clotting disorders, advanced maternal age, and certain infections increase stillbirth risk. These factors can interact rather than act alone.
