Stillbirth is a complex outcome with many potential causes, and in many cases the exact reason remains unknown. Broadly, causes fall into several categories:

• Pregnancy and labor factors
  • Preterm labor or prolonged pregnancy (post-term pregnancy)
  • Placental problems (insufficient blood flow, placental abruption, placental insufficiency)
  • Multiple pregnancies (twins, triplets) with added risk
  • Complications during labor and delivery
• Placental and fetal issues
  • Placental dysfunction or inflammation
  • Fetal growth restriction (inadequate fetal growth)
  • Fetal genetic or congenital anomalies
• Infections
  • Maternal, placental, or fetal infections (e.g., certain bacterial, viral, or parasitic infections)
• Umbilical cord problems
  • Nuchal cord, knots, or compression can reduce oxygen delivery
• Maternal health and chronic conditions
  • Hypertension (high blood pressure), preeclampsia
  • Diabetes or autoimmune conditions
  • Obesity, thyroid disorders, thrombophilia
  • Inadequate or abnormal immune or inflammatory responses
• Environmental and lifestyle factors
  • Substance use (e.g., alcohol, certain drugs)
  • Severe malnutrition or significant exposure to toxins (depending on context)
• Unexplained stillbirth
  • A large proportion of stillbirths have no clearly identifiable cause even after thorough investigation; some studies report that up to roughly half to 60% of cases remain unexplained, with variables such as timing and combination of factors contributing to the outcome

What this means for individuals

• If you are pregnant or planning pregnancy and have concerns about stillbirth risk, it’s important to discuss with a healthcare provider who can review medical history, order appropriate prenatal testing, monitor fetal growth, and manage any chronic conditions.
• Routine prenatal care, screening tests, managing chronic diseases, avoiding harmful substances, and recognizing warning signs (such as decreased fetal movement, severe headache, swelling, vision changes) are critical.

If you’d like, I can tailor this to a specific context (for example, risks during late pregnancy, risk factors for a twin pregnancy, or how stillbirth is investigated after it occurs) and summarize guidance from reputable health sources.