Stillbirth (when a baby dies in the womb after about 20–28 weeks of pregnancy, depending on the country) usually has more than one contributing factor, and in many cases no single clear cause is ever found. That uncertainty can be very painful for parents, but it does not mean anyone did something wrong.

What “stillbirth” means

  • Stillbirth is defined as the death of a baby before birth, after a certain gestational age or weight limit set by local health authorities (often from 20–28 weeks onward).
  • Earlier losses are usually called miscarriages, while stillbirth refers to later pregnancy loss. Termination of pregnancy for medical reasons is classified separately.

Major medical causes

Most known causes fall into a few broad groups, and they often overlap.

  • Placenta and cord problems
    • Placental insufficiency (placenta not delivering enough oxygen or nutrients).
* Placental abruption (placenta separating from the womb too early).

* Umbilical cord issues such as knots, cord being compressed, prolapse, or abnormal insertion, which can suddenly cut off oxygen.
  • Baby’s health conditions
    • Genetic or chromosomal conditions (for example trisomies like Down, Edwards, or Patau syndromes).
* Structural or developmental anomalies (for example severe brain, heart, or organ malformations).

* Fetal growth restriction, where the baby is smaller than expected because of poor oxygen or nutrient supply.
  • Maternal health conditions
    • High blood pressure disorders including chronic hypertension and preeclampsia.
* Diabetes, especially if pre‑existing or poorly controlled.

* Autoimmune or clotting disorders, thyroid disease, obesity, and some kidney or heart diseases.

* Certain infections in pregnancy (for example syphilis, malaria, HIV in some regions, and bacterial or viral infections like group B strep or cytomegalovirus).

Risk factors and patterns

Having a risk factor does not mean a baby will be stillborn, and many parents who experience stillbirth had a completely “low‑risk” pregnancy on paper.

  • Pregnancy circumstances
    • Multiple pregnancy (twins, triplets).
* Very prolonged pregnancy (beyond 41–42 weeks).

* Previous stillbirth, preterm birth, or severe growth restriction in a prior pregnancy.
  • Lifestyle and demographic factors
    • Smoking during pregnancy and, in some studies, heavy alcohol or drug use.
* Very young or older maternal age.

* Limited access to antenatal care, delayed care when symptoms arise, or living in regions with fewer medical resources.

When no cause is found

  • Even after thorough investigations (reviewing the pregnancy, blood tests, placental exam, and often an autopsy), many stillbirths remain “unexplained.”
  • Unexplained does not mean imagined or trivial; it reflects the limits of current tests and knowledge, and parents are rarely to blame for what happened.

What parents can do next

  • Doctors may offer tests on the placenta, cord, and baby, and blood tests for the mother to look for clues; accepting or declining this is a personal decision.
  • For future pregnancies, closer monitoring, treatment of underlying conditions, and individualized birth planning can often reduce risk and provide some reassurance.

If this question is personal, speaking with an obstetrician or maternal–fetal medicine specialist who can review the specific case is very important, both for answers where possible and for planning any future pregnancy.