Intrauterine fetal demise (IUFD) is the death of a fetus inside the uterus before delivery. In the United States, it is generally defined as a fetal death occurring at 20 weeks of gestation or later, and it is commonly referred to as stillbirth. About 1 in 175 pregnancies are affected, totaling roughly 21,000 stillbirths each year in the U.S.
How IUFD Differs From Miscarriage
The distinction between miscarriage and IUFD comes down to timing. A pregnancy loss before 20 weeks is classified as a miscarriage (also called a spontaneous abortion in medical terminology). A loss at 20 weeks or beyond, or when the fetus weighs at least 350 grams, is classified as a fetal death or stillbirth. Most states use the 20-week threshold for reporting purposes. Some international definitions set the line at 28 weeks, which is why statistics can vary depending on the source.
Common Causes
In many cases, no clear cause is ever identified. One retrospective study looking at term singleton pregnancies found that over 60% of IUFD cases were ultimately classified as unexplained. When a cause can be determined, it typically falls into one of several categories.
Umbilical cord abnormalities are among the most frequently identified causes, accounting for about 27% of cases in that same study. Conditions like excessive coiling of the cord can restrict blood flow to the fetus. Placental abruption, where the placenta separates from the uterine wall before delivery, accounted for about 7% of cases. Congenital anomalies, including chromosomal problems and structural malformations, are another recognized cause. Infections affecting either the mother or the intrauterine environment can also lead to fetal death, though this appears to be less common.
Risk Factors
Certain maternal health conditions raise the likelihood of IUFD. Chronic high blood pressure and diabetes that existed before pregnancy are both associated with higher rates of stillbirth, and having both conditions together appears to increase the risk further. Obesity is another well-established risk factor.
Other factors linked to higher risk include smoking during pregnancy, being over age 35, and having had a previous stillbirth. A population-based cohort study found that women with a prior stillbirth have roughly twice the risk of recurrence compared to women whose first pregnancy resulted in a live birth (5.8 per 1,000 versus 3.2 per 1,000). While that elevated relative risk sounds alarming, the absolute risk in a subsequent pregnancy remains low.
Signs and Symptoms
The most common sign is a noticeable decrease or complete stop in fetal movement. Many people describe simply realizing they haven’t felt the baby move in hours or days. Other symptoms can include abdominal pain, vaginal bleeding or unusual discharge, and pelvic pressure. Some people experience no obvious symptoms at all, and the loss is discovered during a routine prenatal visit.
IUFD is definitively diagnosed by ultrasound, which confirms the absence of a fetal heartbeat. There is no blood test or other screening that can make the diagnosis on its own.
What Happens After Diagnosis
Once IUFD is confirmed, the pregnancy still needs to be delivered. Between 14 and 24 weeks, there are two equally safe options: induced labor or a surgical procedure called dilation and evacuation. Induction involves medication to start contractions and deliver vaginally, which takes significantly longer in terms of hospital time. The surgical option is shorter but carries a slightly higher chance of needing a follow-up procedure afterward. Both approaches have similar overall complication rates, and the choice is typically based on gestational age, medical circumstances, and the patient’s preference. Later in pregnancy, induced labor is the standard approach.
There is no medical urgency to deliver immediately in most cases. Providers will discuss timing and options, and in many situations, parents have some time to process what has happened before making decisions.
Testing to Determine the Cause
After a stillbirth, a series of evaluations is recommended to try to identify why it happened. The gold standard workup includes three main components: a fetal autopsy, microscopic and visual examination of the placenta and umbilical cord, and genetic testing of fetal tissue. Genetic material can be collected from umbilical cord blood, amniotic fluid, placental tissue, or fetal muscle.
Maternal blood work is also part of the evaluation. This can include testing for infections, screening for blood clotting disorders (thrombophilia), checking blood sugar control, thyroid function, and a test called Kleihauer-Betke that detects whether fetal blood cells crossed into the mother’s bloodstream. Even with this comprehensive workup, a significant number of cases remain unexplained, which can be one of the most difficult aspects for families.
Prevention and Fetal Movement Monitoring
Prevention strategies focus on managing modifiable risk factors. Quitting smoking, managing chronic conditions like diabetes and high blood pressure before and during pregnancy, and sleeping on your side (rather than your back) in the third trimester are all associated with lower risk.
Fetal movement counting, sometimes called “kick counts,” is widely discussed as a monitoring tool. The idea is that a noticeable decrease in movement could serve as an early warning. In practice, however, randomized trials have not found a direct link between routine fetal movement counting and a reduction in stillbirth rates. That said, being generally aware of your baby’s movement patterns and reporting significant changes to your provider is still considered reasonable. The key distinction is between structured daily counting programs, which lack strong evidence, and simply paying attention to what feels normal for your pregnancy.
Since the 1940s, improvements in maternity care have dramatically reduced stillbirth rates. In recent decades, advances have particularly lowered the number of late-term stillbirths. However, the overall rate of decline has slowed in recent years, with the U.S. rate sitting at about 5.7 per 1,000 births as of 2021.
Subsequent Pregnancies
For those who become pregnant again after a stillbirth, the experience is often shaped by anxiety alongside hope. The roughly two-fold increase in relative risk means that monitoring in a subsequent pregnancy is typically more intensive, with more frequent ultrasounds and closer surveillance in the third trimester. Despite the elevated relative risk, the vast majority of pregnancies following a stillbirth do result in a healthy delivery. The absolute recurrence rate of about 5.8 per 1,000 means that over 99% of subsequent pregnancies in this group do not end in another stillbirth.