What are the causes of stillbirth?
There are a number of known causes of stillbirth. Sometimes more than one of these causes may contribute to the baby’s death. Common causes include:
- Birth defects: About 15 to 20 percent of stillborn babies have one or more birth defects (1). At least, 20 percent of these have chromosomal disorders, such as Down syndrome (1). Others have other birth defects resulting from genetic, environmental or unknown causes.
- Placental problems: Placental problems cause about 25 percent of stillbirths (3). One of the most common placental problems is placental abruption. In this condition, the placenta peels away, partly to almost completely, from the uterine wall before delivery. It results in heavy bleeding that can threaten the life of mother and baby. Sometimes it can cause the fetus to die from lack of oxygen. Women who smoke cigarettes or use cocaine during pregnancy are at increased risk of placental abruption.
- Poor fetal growth: Fetuses who are growing too slowly are at increased risk of stillbirth. About 40 percent of stillborn babies have poor growth (2). Women who smoke cigarettes or have high blood pressure are at increased risk of having a baby that grows too slowly. An ultrasound examination during pregnancy can show that the fetus is growing poorly, allowing health care providers to carefully monitor the pregnancy.
- Infections: Infections involving the mother, fetus or placenta appear to cause about 10 to 25 percent of stillbirths (4, 5). Infections are an important cause of fetal deaths before 28 weeks of pregnancy (4). Some infections may cause no symptoms in the pregnant woman. These include genital and urinary tract infections and certain viruses, such as fifth disease (parvovirus infection). These infections may go undiagnosed until they cause serious complications, such as fetal death or preterm birth (before 37 completed weeks of pregnancy).
- Chronic health conditions in the pregnant woman: About 10 percent of stillbirths are related to chronic health conditions in the mother, such as high blood pressure, diabetes, kidney disease and thrombophilias (blood clotting disorders) (5). These conditions may contribute to poor fetal growth or placental abruption.
- Umbilical cord accidents: Accidents involving the umbilical cord may contribute to about 2 to 4 percent of stillbirths (3). These include a knot in the cord or abnormal placement of the cord into the placenta. These can deprive the fetus of oxygen.
Other causes of stillbirth include trauma (such as car accidents), postdate pregnancy (a pregnancy that lasts longer than 42 weeks), Rh disease (an incompatibility between the blood of mother and baby), and lack of oxygen (asphyxia) during a difficult delivery. These causes are uncommon.
Certain risk factors also are associated with stillbirth. Some of these include (1, 4, 5):
A recent study found that African-American women had a two-fold increased risk of stillbirth compared to white women (6). It is not known why African-American women are at higher risk. The risk for Hispanic women was similar to that of non-Hispanic white women (6)