What Causes Second Trimester Intrauterine Fetal Death (IUFD)?
Intrauterine fetal death (IUFD) is a concern in high-risk pregnancies. Although there are some known causes and risk factors, many cases of second trimester IUFD do not present classically and a clear cause of IUFD is not always found. This means it’s important to partner with a team of maternal fetal medicine specialists to get the care you need and ensure you take the right steps to prevent complications.
What is Intrauterine Fetal Death?
Fetal death in utero, commonly known as stillbirth, is categorized based on how far along it occurs during pregnancy. Generally,
- Early stillbirth occurs between 20 and 27 weeks gestation
- Late stillbirth occurs between 28 and 36 weeks gestation
- Term stillbirth occurs after 37 weeks gestation3
Second trimester intrauterine fetal death is typically recognized as a demise after 20 weeks of gestation and a fetal weight of more than 500 grams. It affects about 1 in 100 pregnancies each year in the United States,4 and the rate has declined by more than 25% in the last 15 years.1
What’s the Difference Between IUFD and Miscarriage?
Generally, a pregnancy loss during the first- and early-second trimester (before 20 weeks) is classified as a miscarriage.3 However, this definition is somewhat arbitrary and many causes of miscarriage overlap with those of IUFD, and the workup is often similar.
IUFD Risk Factors
There are some known risk factors that have been linked to IUFD. These include:
- Racial group (especially non-Hispanic black)
- Comorbidities such as hypertension and diabetes
- Multiple gestations
- Advanced maternal age (older than 35 years)
- A history of pregnancy complications like preterm delivery, growth restriction, and preeclampsia
- Exposures in pregnancy such as alcohol use, smoking, and drug use2
It’s important to note that these factors do not necessarily cause IUFD, but that stillbirths occur more frequently in the above groups because of many different factors.3
Causes of Second Trimester IUFD
Because it can be difficult to specifically classify stillbirth, more study is needed on the potential causes of IUFD. In many cases, there is no standardized method for determining the cause of pregnancy loss. However, even when evaluated, a clear cause is not always found.2 Some common causes of second trimester IUFD include:
- Placental Insufficiency
- Placental Abruption
- Fetal Infection
- Genetic Abnormalities of the fetus
- Congenital Anomalies of the fetus
- Fetomaternal Hemorrhage
- Umbilical Cord Complications
Placental insufficiency is likely in pregnancies that have early growth restriction, bleeding, or low amniotic fluid (oligohydramnios). A fetus with apparent abnormalities likely has a genetic or anatomic cause for IUFD. A patient with a hematoma and bleeding may also have placental abruption (separation).
What Happens After Stillbirth?
A number of options are available based mostly on the mother’s preferences and gestational age. The two most common options for women with IUFD are labor induction or removal of the pregnancy (using Dilation and Evacuation, or D&E). In some rare cases, cesarean delivery can be performed.2
After one of the above procedures, it’s important to perform a number of tests to ensure the health of the mother and assess her chances of future healthy pregnancies by limiting risk factors and causes. A fetal autopsy is the most likely test to reveal a cause of IUFD, but some parents are uncomfortable with this. Amniocentesis can be performed to screen for genetic conditions that may have been causative. Additionally, the placenta should be examined.4 Then, a maternal fetal medicine specialist can help determine the mother’s next steps in family planning and further pregnancies.
Schedule a Consultation
Our award-winning team of maternal fetal medicine specialists can provide expert care in high-risk pregnancies in the New York City area. To schedule an appointment and learn more, we invite you to contact our office by calling or filling out our online form.
- Society for Maternal Fetal Medicine
- American College of Obstetricians and Gynecologists
- Centers for Disease Control and Prevention
- March of Dimes (National Foundation for Infantile Paralysis)
Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!