Stillbirth is one of the most devastating experiences any family can face. Understanding the causes of stillbirth not only helps parents make informed decisions but also empowers them to advocate for proper prenatal care. While not all stillbirths are preventable, awareness of risk factors can lead to earlier detection and intervention. Many expectant parents also use tools like a baby heart rate monitor at home for added reassurance between checkups, although this should never replace professional medical evaluation.

Because stillbirth can have multiple causes, doctors carefully examine maternal health, fetal development, and placental function to determine what may have happened. This guide breaks down the major categories, helping parents gain clarity and understanding during an incredibly difficult time.

Defining the Tragedy: What Stillbirth Is and How It’s Categorized

Stillbirth is defined as the loss of a baby after 20 weeks of pregnancy (in many countries) or after 28 weeks (per WHO standards). It is typically categorized into:

• Early stillbirth: 20–27 weeks
• Late stillbirth: 28–36 weeks
• Term stillbirth: 37+ weeks

These categories help physicians determine possible causes and patterns. While medical investigation cannot erase the pain of loss, identifying a cause—when possible—can offer closure and guide future pregnancy care.

Stillbirth is not the same as miscarriage, which occurs before 20 weeks. Because the baby is usually fully formed and often viable earlier in pregnancy, determining medical factors becomes essential for understanding what went wrong.

Placenta Problems: When the Fetal Life Support System Fails

The placenta is the primary source of oxygen and nutrition for the developing baby. If it fails to function properly, complications can become life-threatening in utero.

Common Placental Issues Leading to Stillbirth

• Placental abruption – when the placenta detaches from the uterus too early
• Placental insufficiency – when the placenta does not deliver enough oxygen or nutrients
• Placenta previa – when the placenta blocks the cervix, increasing risk of bleeding
• Blood clotting disorders affecting the placenta

Placental problems are among the most common causes of stillbirth. Symptoms may include reduced fetal movement, bleeding, or severe abdominal pain. Because many issues develop gradually, regular prenatal checkups and fetal monitoring are crucial for early detection.

Fetal Growth Restriction (FGR): Underdevelopment and Intrauterine Malnutrition

Fetal Growth Restriction (FGR), sometimes called Intrauterine Growth Restriction (IUGR), occurs when a baby does not grow at the expected rate during pregnancy. When the baby becomes too small or cannot develop critical organs properly, it increases the risk of stillbirth—especially in the third trimester.

Causes of FGR include:

• Poor placental function
• Maternal hypertension
• Smoking or substance use
• Nutritional deficiencies
• Chromosomal abnormalities

Doctors monitor FGR using ultrasound measurements, Doppler studies, and growth charts. In some cases, early delivery is recommended to protect the baby from complications inside the womb.

Infections During Pregnancy: Maternal or Fetal Illness as a Critical Factor

Both maternal and fetal infections can lead to serious complications, including stillbirth. Some infections may show mild symptoms or none at all, making screening essential.

Infections linked to stillbirth include:

• Group B Streptococcus (GBS)
• Listeria
• Toxoplasmosis
• Cytomegalovirus (CMV)
• Syphilis
• Parvovirus B19
• Severe viral infections, including influenza and COVID-19 in certain cases

Infections can cause inflammation, fever, placental damage, or direct harm to the fetus. Early detection through routine prenatal tests and proper treatment greatly reduces the risk.

Maternal Health Conditions: Diabetes, Hypertension, and Thyroid Disorders

Maternal health plays a major role in pregnancy outcomes. Chronic illnesses, if poorly managed, can significantly increase stillbirth risk.

High-risk maternal conditions include:

• Diabetes (Type 1, Type 2, or gestational)
• Hypertension and preeclampsia
• Thyroid disorders (hypothyroidism or hyperthyroidism)
• Kidney disease
• Autoimmune disorders (like lupus)
• Severe anemia

Uncontrolled diabetes can lead to placental insufficiency or very large babies who are at higher risk during pregnancy and delivery. Hypertension and preeclampsia can reduce blood flow to the placenta or cause placental abruption.

Women with preexisting medical conditions should receive specialized prenatal care, often including more frequent ultrasounds and fetal monitoring.

Umbilical Cord Accidents: Torsion, Prolapse, and Knotting Issues

Umbilical cord accidents (UCAs) are unpredictable events where the cord becomes compressed or restricted, cutting off oxygen to the baby. These cases are often sudden and may occur even in otherwise healthy pregnancies.

Common cord-related complications:

• True knots in the cord
• Nuchal cord (cord wrapped around baby’s neck—usually harmless but occasionally problematic)
• Cord prolapse (cord slips into the birth canal before the baby)
• Cord torsion or twisting
• Tight cord loops

While most cord issues are harmless, some restrict blood flow. Reduced fetal movement is often the first sign that something may be wrong, which is why daily movement monitoring during late pregnancy is encouraged.

Genetic and Chromosomal Abnormalities in the Developing Fetus

Some stillbirths occur because of genetic or chromosomal conditions that prevent normal fetal development. These abnormalities may result in structural defects, organ failure, or developmental delays incompatible with life.

Possible genetic causes include:

• Trisomy 13, 18, or 21
• Turner syndrome
• Structural abnormalities of the brain, heart, or kidneys
• Rare inherited genetic disorders

These issues may be detected through:

• Prenatal screening (NIPT)
• Ultrasound anatomy scans
• Diagnostic tests like amniocentesis

Families affected by genetic abnormalities may be referred to a genetic counselor for guidance and support in future pregnancies.

Unexplained Cases: When Even Extensive Investigation Yields No Clear Cause

Despite modern medical technology, about 25–40% of stillbirths remain unexplained. This can be one of the most painful outcomes for families because it leaves unanswered questions.

Possible reasons for an unexplained stillbirth include:

• Subtle infections not detectable after birth
• Placental abnormalities too small to identify
• Rare metabolic or genetic disorders
• Sudden fetal cardiac issues
• Unknown complications unrelated to maternal health

Not having an answer does not mean the parents did anything wrong. Many parents in this situation go on to have healthy pregnancies in the future with closer monitoring and supportive care.

Conclusion

Stillbirth is a heartbreaking and complex tragedy with many possible causes, ranging from placental problems to genetic conditions. Understanding these factors can guide parents, support healing, and help in planning for safer future pregnancies. Awareness, regular prenatal checkups, and early recognition of symptoms play a crucial role in reducing risk.

While at-home tools like a baby heart rate monitor can offer peace of mind, medical guidance and routine prenatal visits are always the most reliable way to ensure fetal wellbeing. By staying informed and supported, families can move forward with greater confidence and hope.