[10] The term is in contrast to miscarriage, which is an early pregnancy loss,[11] and sudden infant death syndrome, where the baby dies a short time after being born alive.

[2]: Causes tab, [3][13] Risk factors include a mother's age over 35, smoking, drug use, use of assisted reproductive technology, and first pregnancy.

[20] Many stillbirths occur at full term to apparently healthy pregnant women, and a postmortem evaluation reveals a cause of death in about 40% of autopsied cases.

[28] In the United States, highest rates of stillbirths happen in pregnant women who:[29] It is unknown how much time is needed for a fetus to die.

[34] If the fetus is alive but inactive, extra attention will be given to the placenta and umbilical cord during ultrasound examination to ensure that there is no compromise of oxygen and nutrient delivery.

[37] To allow comparison, the World Health Organization uses the ICD-10 definitions and recommends that any baby born without signs of life at greater than or equal to 28 completed weeks' gestation be classified as a stillbirth.

[38] The term is often used in distinction to live birth (the baby was born alive, even if they died shortly thereafter) or miscarriage (early pregnancy loss[37]).

[42] Some maternal factors are associated with stillbirth, including being age 35 or older, having diabetes, having a history of addiction to illegal drugs, being overweight or obese, and smoking cigarettes in the three months before getting pregnant.

[44] After two weeks, the pregnant woman is at risk of developing blood clotting problems, and labor induction is recommended at this point.

[56] The vast majority of stillbirths worldwide (98%) occur in low- and middle-income countries, where medical care can be of low quality or unavailable.

[59][page needed] In many countries, parents are expected by friends and family members to recover from the loss of an unborn baby very soon after it happens.

[10] Further psycho-social effects on parents include apprehension, anger, feelings of worthlessness and not wanting to interact with other people, with these reactions sometimes carried over into pregnancies that occur after the stillbirth.

[60] Men also suffer psychologically after stillbirth, although they are more likely to hide their grief and feelings and try to act strong, with the focus on supporting their partner.

[62] In Austria, a stillbirth is defined as a birth of a child of at least 500g weight without vital signs, e.g. blood circulation, breath or muscle movements.

[64] The definition of "fetal death" promulgated by the World Health Organization in 1950 is as follows: In Germany, a stillbirth is defined as the birth of a child of at least 500g weight without blood circulation or breath.

In the Netherlands, stillbirth is defined differently by the Central Bureau of Statistics (CBS) and the Dutch Perinatal Registry (Stichting PRN[68]).

[70] They register all liveborn and stillborn children from 22, 24 or 28 weeks of gestation and onwards (dependent on the report: fetal, neonatal or perinatal mortality).

For the purposes of the Births and Deaths Registration Act 1926 (as amended), section 12 contains the definition:"still-born" and "still-birth" shall apply to any child which has issued forth from its mother after the twenty fourth week of pregnancy and which did not at any time after being completely expelled from its mother, breathe or show any other signs of life.A similar definition is applied within the Births and Deaths Registration Act 1953 (as amended), contained in s.41.

In Northern Ireland, the Births and Deaths Registration (Northern Ireland) Order 1976,[77] as amended contains the definition:"still-birth" means the complete expulsion or extraction from its mother after the twenty-fourth week of pregnancy of a child which did not at any time after being completely expelled or extracted breathe or show any other evidence of life.Registration of stillbirths can be made by a relative or certain other persons involved with the stillbirth but it is not compulsory to do so.

[65] In the U.S., the Born-Alive Infants Protection Act of 2002 specifies that any breathing, heartbeat, pulsating umbilical cord or confirmed voluntary muscle movement indicate live birth rather than stillbirth.

[81] The Centers for Disease Control and Prevention collects statistical information on "live births, fetal deaths, and induced termination of pregnancy" from 57 reporting areas in the United States.

[83] Researchers are learning more about the long term psychiatric sequelae of traumatic birth and believe the effects may be intergenerational[84] The CDC states that, in the US, a stillbirth is typically defined as the loss of a fetus during or after the 20th week of pregnancy.

Only 11 areas specifically use the term 'stillbirth', often synonymously with late fetal death; however, they are split between whether stillbirths are "irrespective of the duration of pregnancy", or whether some age or weight constraint is applied.