Stillbirth refers to the death of a fetus at or after the 20th week of pregnancy.
There are many causes of stillbirth, ranging from birth defects to problems with the pregnancy. Often, health care providers cannot determine a specific cause for a particular stillbirth.
The NICHD supports research on many of the causes of stillbirth, its occurrence in populations, risk factors, and ways to prevent it from happening.
Medical or Scientific Names
- Fetal death
- Fetal demise
Stillbirth: Topic Information
What is stillbirth?
- Before labor. Death can happen inside the womb, before labor begins. This kind of stillbirth is called an antepartum stillbirth. In the United States, most stillbirths occur before the start of labor.4
- During labor. Death can also happen during labor. This is an intrapartum stillbirth. The causes of these stillbirths tend to be different than the causes of stillbirths before labor.4
Sometimes fetal deaths and infant deaths in the first week or first months of life are grouped together, even though they may occur at different times. When these deaths are looked at together, they are called perinatal (pronounced per-uh-NEYT-l) deaths, meaning “around the time of birth.” This is because some of the same problems and risks can lead to a death either before or just after birth.5
The death of a fetus before the 20th week of pregnancy is usually called a miscarriage or pregnancy loss. Learn more at the Pregnancy Loss A-Z topic.
How common is stillbirth?
Stillbirths in the United States
In 2006, the most recent year for which U.S. data are available, 1 out of every 167 pregnancies that made it to the 20th week ended with the death of the fetus before birth (that is, stillbirth before delivery). This translates to a total of nearly 26,000 deaths. About one-half of these stillbirths took place at 28 weeks of pregnancy or later.1
In the United States, there are similar numbers of stillbirth deaths and deaths of infants during their first year of life.1,2 That is, about one-half of all deaths between 20 weeks of pregnancy and the first birthday occur before delivery.
On average, the U.S. stillbirth rate has been going down. For example, in 1985, almost 1 of every 127 pregnancies that made it to week 20 ended as a stillbirth before delivery;1 in 1950, the rate was about 1 of every 53 such pregnancies.3
Using the World Health Organization definition for stillbirth, which counts stillbirths only from 28 weeks of pregnancy, there were 2,600,000 stillbirths around the world in 2009, the most recent year for which worldwide data on stillbirth are available. This translates to an average of about one stillbirth at or after 28 weeks for every 45 births in 2009.4
The stillbirth rate is highest in South Asia and Sub-Saharan Africa (about 1 stillbirth at the 28th week of pregnancy or later per 33 births). The rate is lowest in high-income countries—fewer than 1 per 250 births.4
What are the risk factors for stillbirth?
Stillbirth can happen in any pregnancy. Even after a thorough investigation, a probable or possible cause of stillbirth may not be found.1
Even though there are certain risk factors for stillbirth, most individual stillbirths in the United States are not linked to any known risk factors that the woman has at the time she learns she is pregnant.2
Risks for Stillbirth in High-Income Countries
Studies have found many factors that increase risk for stillbirths in the United States and other high-income countries.
- Low socioeconomic status
- Older age (older than age 35)
- Smoking tobacco or marijuana during or just before pregnancy, or exposure to secondhand smoke during pregnancy
- Using illegal drugs before or during pregnancy
Maternal Medical Conditions
- Being overweight or obese
- Diabetes before pregnancy
- High blood pressure before pregnancy
Maternal Reproductive History
- Never having given birth before
- Previous stillbirth or small for gestational age infant
- Pregnancy with twins, triplets, or other multiples
- Assisted reproductive technology
- Small size in the fetus, given its age (sometimes called small for gestational age [SGA]). SGA can sometimes be due to growth restriction, a risky condition in which there is a problem with the pregnancy that prevents the fetus from growing as well as it could otherwise.
Risks for Stillbirth in Resource-Limited Countries
In developing countries, lack of access to obstetrical care contributes to high stillbirth rates. Most stillbirths in the developing world result from long and difficult labor, preeclampsia, and infections.5
A study conducted by the Global Network for Women’s and Children’s Health Research (funded by the NICHD and the Bill and Melinda Gates Foundation) showed that providing basic newborn care training to birth attendants in low-income countries makes the stillbirth rate plummet. As a result of the intervention, the rate of stillbirths dropped from 1 per every 43 deliveries to about 1 per 63 deliveries. The researchers believed this improvement was due to an increase in babies being resuscitated if they were not breathing at birth—a common problem that an untrained birth attendant might classify as a stillbirth. However, trained birth attendants can treat this problem using resuscitation techniques, including rubbing the newborn’s back.6,7
What are possible causes of stillbirth?
In addition to risk factors that can increase the likelihood of a stillbirth, there are also factors that can cause or contribute to stillbirth. Remember, though, that in some cases of stillbirth, the cause of death remains unknown even after extensive testing.
To learn more about the possible causes of and contributors to stillbirth, the NICHD-supported Stillbirth Collaborative Research Network (SCRN) examined more than 500 stillbirths that occurred in 59 medical centers around the United States over 2½ years. In almost one-quarter of these cases, the researchers could not determine a probable or even a possible cause of death. Also, many of the stillbirths had more than one likely cause.
The likely causes of and contributors to stillbirth identified by the study are listed below in order from most common to least common:1
- Pregnancy and labor complications. Problems with the pregnancy likely caused almost one in three stillbirths. These complications included preterm labor, pregnancy with twins or triplets, and the separation of the placenta from the womb (also called “placental abruption;” the placenta provides nutrients and oxygen to the fetus). Pregnancy and labor complications were more common causes of stillbirths before week 24.
- Problems with the placenta. Almost one in four stillbirths were likely caused by problems with the placenta. One example of a placental problem that causes stillbirth is insufficient blood flow to the placenta. In the SCRN study, placental problems were the leading cause of stillbirths that took place before birth, and these deaths tended to occur after 24 weeks of pregnancy.
- Birth defects. In more than 1 of every 10 stillbirths, the fetus had a genetic or structural birth defect that probably or possibly caused the death.
- Infection. In more than 1 of every 10 stillbirths, the death was likely caused either by an infection in the fetus or in the placenta, or by a serious infection in the mother. Infections were a more common cause of death in stillbirths before week 24 than in those after.
- Problems with the umbilical cord. Problems with the umbilical cord were considered a probable or possible cause of about 1 in 10 stillbirths. For example, the cord can get knotted or squeezed, cutting off oxygen to the developing fetus. This cause of stillbirth tends to occur more toward the end of pregnancy.
- High blood pressure disorders. High blood pressure in the mother—whether due to chronic high blood pressure or to preeclampsia—also contributed to stillbirths. These types of stillbirths were more common in the end of the second trimester and the beginning of the third, compared with other parts of pregnancy.
- Medical complications in the mother. Problems with the mother’s health—such as diabetes—were considered a probable or possible cause in fewer than 1 in 10 of the stillbirths.
This research also showed that:
- Women who experienced financial, emotional, or other personal stress in the year before their delivery had an increased chance of having a stillbirth.
- Smoking tobacco or marijuana, taking prescription painkillers, or using illegal drugs during pregnancy is associated with double or even triple the risk of stillbirth.
In the United States, stillbirths are more than twice as likely among black women than among white women.2 However, the reasons for this are not entirely clear.
The SCRN study found that the most common causes of stillbirth were different for black women than for white women. Compared with stillbirths experienced by white women and Hispanic women, stillbirths to non-Hispanic black women tended to be caused by infection or by complications of pregnancy and labor. Also, in black women, stillbirth was more likely to occur during (rather than before) labor and earlier than 24 weeks into the pregnancy.1
As mentioned above, SCRN research found that stillbirth was more than twice as likely among women who had experienced major financial, emotional, traumatic, or partner-related events in the year before delivery than among women who had not. Black women were more likely than women in general to have experienced at least three such stressful events in the past year.3
How is stillbirth diagnosed?
A pregnant mother may suspect stillbirth if she stops feeling the fetus kick or make other active movements inside her womb. But not feeling movement does not mean stillbirth in all cases.1
Before birth, the only way to know for sure whether a stillbirth has occurred is to determine if the fetus’s heart is beating. This is often done using ultrasound,2 a type of imaging that projects harmless sound waves through the mother’s body to create an image.
After birth, the infant is considered stillborn if he or she has “no signs of life,” which means the infant:3
- Is not breathing
- Has no heartbeat
- Has no pulsations in the umbilical cord, and
- Does not make voluntary movements
How do health care providers manage stillbirth?
After a stillbirth, health care providers will try to determine why the fetus died and help the family cope with their loss.
Later on, if the family wants to try for another pregnancy, providers can help the mother understand and change any problems that might increase her risk of another stillbirth.
If health care providers determine that the fetus has died while it is still in the womb, the next step is to deliver it. In general, this does not have to happen right away. Some parents might need time to cope with the news of their loss or to make arrangements. Others might prefer to complete the process as soon as possible.1
Depending on how far along the pregnancy is and other considerations, health care providers usually will use one of these two methods to deliver the fetus:1
- Induction. Providers will give the mother medicine to start labor. This method is used more often later in pregnancy.
- Dilation and evacuation. In this surgical procedure, providers first help the woman’s cervix open, or dilate. After about a day, the cervix will have opened and providers give the woman a medicine to keep her from feeling pain. Then, they insert instruments through the vagina and cervix into the womb to remove the fetus, the placenta, and other pregnancy material. Dilation and evacuation is only an option in the second trimester.
After a stillbirth, it is important for providers to examine the body closely. Figuring out why the stillbirth occurred, if possible, can help providers and parents understand any risks that might affect future pregnancies.
Health care providers might examine a stillborn baby in three main ways:1
- Inspecting the exterior of the fetus, placenta, and tissues. First, providers will examine the body and the tissues that surrounded and nourished the fetus inside the womb. This examination can reveal problems that could have caused or contributed to the death. They may weigh and measure the body and placenta to look for any growth problems. The health care provider might also photograph certain parts of the body or the placenta to put in the medical record or to show to a specialist.
- Examining individual cells and genetic material. Health care providers may ask parents’ permission to take samples of tissues from the body, the fluid that surrounded it in the womb (amniotic fluid), the placenta, and the umbilical cord. A laboratory will examine these samples for problems with cells, chromosomes, and DNA that could have caused or contributed to the death.
- Autopsy. Health care providers may ask parents’ permission to do an autopsy. (If providers do not bring it up, parents can also ask for an autopsy.) An autopsy involves opening up parts of the body to look for problems with the brain, heart, or other organs.
If parents prefer not to do an autopsy, the provider might ask for permission to take X-rays or conduct another type of imaging that shows inside the body. Imaging can help find the cause of death.1
In many cases of stillbirth, there are no obvious risk factors. If there are factors that might increase the risk of another stillbirth in the future, and if the mother wants to have another child, she can work together with her providers to attempt to control the risks before getting pregnant again.1 Learn more about risk factors for stillbirth.
Losing a baby to stillbirth can be a difficult experience for a family. Health care providers may offer ways to help parents come to terms with the death. Providers may also refer parents to a support group, religious leader, or counselor for help.1 Read more about coping with grief after stillbirth.
Stillbirth: Research Goals
The NICHD’s research goals related to stillbirth include:
- Understanding the causes of stillbirths
- Detailing the demographic and population factors related to stillbirth
- Improving prediction of stillbirth risk
- Improving stillbirth post-mortem examination and reporting
- Outlining evidence-based measures to prevent or reduce stillbirth
- Linking in utero developmental phenotypes to gene expression, epigenetic changes, maternal physiology, and environmental exposures
- Improving our understanding of the morphology, function, genetics, and metabolism of the placenta and uterine blood flow
- Improving methods for antenatal diagnosis of placental disease or fetal health conditions that increase risk of stillbirth
Stillbirth: Research Activities and Scientific Advances
Through its intramural and extramural organizational units, the NICHD conducts and supports a broad range of research projects on stillbirth. Short descriptions of this research are included below.
A large portion of the Institute’s support for research on stillbirth is provided through the extramural Pregnancy and Perinatology Branch (PPB), whose interests encompass all research that seeks to improve health outcomes associated with pregnancy, birth, and early infancy. The PPB supported the Stillbirth Collaborative Research Network (SCRN), which was founded to examine the etiology and epidemiology of stillbirth.
The Network has made some important findings, including the following:
- An SCRN study compared the use of illicit drugs and cigarettes in U.S. pregnancies with and without stillbirth. They found that a pregnant mother’s use of cigarettes, marijuana, or other illicit drugs and her exposure to secondhand smoke were linked to an increased risk of stillbirth. (PMID: 24463671)
- SCRN researchers compared microarray analysis to the standard karyotyping for examining stillborn fetuses’ genetic material and found that microarrays may help detect abnormalities in 40% more cases than the traditional method. (PMID: 23215556)
- One Network study of women giving birth in 59 hospitals around the country found that about one-half of stillbirths were caused by pregnancy complications and conditions affecting the placenta, although most were not linked to any known risk factors the women had at the beginnings of their pregnancies. (PMID: 22166606)
- Another SCRN study found that stressful events in the mother’s life 1 year prior to delivery seemed to increase risk of stillbirth. (PMID: 23531847)
Outside of the SCRN, other recent PPB-supported grants have studied new methods and biomarkers for predicting stillbirth and other adverse outcomes to the fetus. Additional areas of recent support include the risks of smoking, maternal infections, and overweight/obesity during pregnancy as well as the benefits of interventions for these risks. One Branch-supported investigator recently developed an experimental vaccine that significantly reduces stillbirths among rodents that were born to mothers infected with cytomegalovirus (CMV). If pregnant women become infected with the virus, it can result in stillbirth or other negative consequences in the fetus, and currently no preventive measures are available. (PMID: 17299708)
NICHD also supports the Global Network for Women’s and Children’s Health Research, which tests cost-effective interventions to improve maternal and infant health outcomes, including stillbirth, in resource-poor settings. Recently, a Global Network training program for health care workers in six resource-poor countries resulted in a sharp drop in the rate of stillbirths among mothers attended by workers who had been trained through the program, from 23 stillbirths per 1,000 deliveries to fewer than 16 stillbirths per 1,000 deliveries. This was most likely due to a drop in deaths among newborns who would not have taken a breath on their own without resuscitation from the trained attendants, the researchers concluded. (PMID: 20164485)
This training program has now grown into the Helping Babies Breathe initiative, a newborn-care education project active in more than 30 low-income countries around the world. The NICHD is one of several international partners leading this initiative, which shows health care providers resuscitation techniques and other basics of newborn care for the first minute of life. The goal of Helping Babies Breathe is to have at least one person with newborn resuscitation skills attending the birth of every baby in the world. Learn more about the NICHD’s role in the Helping Babies Breathe initiative.
The Division of Intramural Population Health Research (DIPHR)—formerly the Division of Epidemiology, Statistics, and Prevention Research (DESPR)—also conducts research on factors affecting risk for stillbirth, primarily through these three studies:
- Longitudinal Investigation of Fertility and the Environment (LIFE) Study
The LIFE Study is designed to examine the relationship between ubiquitous environmental chemicals, lifestyle, and human fecundity and fertility, including stillbirth and other pregnancy outcomes.
- Effects of Aspirin in Gestation and Reproduction (EAGeR) Study
This multisite, randomized placebo-controlled clinical trial is designed to evaluate the effect of daily low-dose aspirin on live-birth rates. Stillbirth is one of the outcomes it is evaluating.
- Consortium on Safe Labor
This observational study of more than 200,000 deliveries aimed to explore contemporary labor progression and the use of cesarean section. Although stillbirth was not a primary focus of the study, the researchers have collected and published data on risk factors for stillbirth.
In addition to the efforts of PPB and DIPHR, other NICHD organizational units support or conduct research with relevance to stillbirth. For example:
- The Fertility and Infertility (FI) Branch, as part of its portfolio on the mechanisms of fertility and treatments for infertility, supports research on the very early processes in embryonic development that result in aneuploidy, which can cause stillbirth.
- The Maternal and Pediatric Infectious Disease Branch (MPIDB) focuses on HIV and other infectious diseases (including CMV) in pregnant women and children. The MPIDB supports research on the effects of antiretroviral drugs during pregnancy on pregnancy outcomes such as stillbirth.
- The Stillbirth Collaborative Research Network (SCRN), supported by the PPB, was established in 2003 to understand the causes of stillbirth, improve stillbirth reporting, and develop preventive interventions for the condition. In addition, the SCRN is leading to the standardization of reporting procedures and post-mortem examination protocols, which allow more accurate data on the topic.
- The Prenatal Alcohol and SIDS and Stillbirth (PASS) Network, supported by the PPB and two other NIH Institutes, conducts community-linked studies to investigate the role of prenatal alcohol exposure in the risk for SIDS and adverse pregnancy outcomes, such as stillbirth and fetal alcohol spectrum disorders, and how they may be interrelated.
- The Global Network for Women and Children’s Health Research, a partnership between the NICHD, the Bill and Melinda Gates Foundation, and other organizations, is committed to improving maternal and infant health outcomes and building health research capacity in resource-poor settings by testing cost-effective, sustainable interventions for adverse maternal and child health outcomes such as stillbirth.
- The Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-be (nuMoM2b), supported by the PPB, aims to study the underlying causes of adverse pregnancy outcomes (preterm birth, preeclampsia, fetal growth abnormalities, and stillbirth) among a cohort of 10,000 women in their first pregnancy. This prospective observational study is expected to lead to a better understanding of how genetics, biomarkers, environmental exposures, and psychosocial factors interact to result in these adverse outcomes. The recruitment and ascertainment of outcomes of the final cohort was completed in September 2014. A substudy of nuMoM2b—co-funded by the National Heart, Lung, and Blood Institute—is studying the effect of sleep disordered breathing during pregnancy and various sleep parameters, including sleep position, on these adverse pregnancy outcomes.
- The Maternal-Fetal Medicine Units (MFMU) Network, supported by the PPB, is conducting a trial of women who are diagnosed with primary cytomegalovirus (CMV) infection early in pregnancy. Primary CMV infection is associated with stillbirth, placental damage, and poor fetal growth. This trial is studying whether treatment with hyperimmune CMV globulin versus placebo decreases CMV infection and consequences in the offspring.