Deciphering Stillbirth: Common Causes and Tests

When something bad happens, human nature asks the question “why?” When couples experience a stillbirth, these questions can be overwhelming. Take a look at some common queries and answers.

From small losses to horrible tragedies, it’s natural to want to understand how and why some things happen. For parents who have lost a baby to stillbirth (defined as pregnancy loss from the twentieth week to delivery of the baby), the shock and sadness are overwhelming.

The mother often struggles with feelings of guilt. “In the absence of a concrete explanation for what has gone wrong and why, it’s easy for mothers who have experienced a loss to blame themselves for their babies’ deaths,” write Ann Douglas and Dr. John R. Sussman, MD, authors of Trying Again: A Guide to Pregnancy After Miscarriage, Stillbirth, and Infant Loss.”

Unfortunately, why stillbirth happens remains a mystery of modern science. Dr. Cathy Spong, MD, chief of the Pregnancy and Perinatology Branch at the National Institute of Child and Human Development (NICHD), says, “Currently, it’s very hard to come up with answers [about why stillbirth happens] and offer how we can prevent it from happening again. As a physician, I want to be able to promise high-risk patients that we can assure them a healthy baby, but I know that I can’t promise that.”

One of the main challenges researchers face is that stillbirth is defined differently state by state. “It’s also underreported,” asserts Dr. Spong. “Fetal death reports are not required. So we are left asking, ‘How big is the problem?'”

The MISS Foundation, a national non-profit organization that helps parents who have lost an infant or child, reports that about 30,000 babies are stillborn each year. Approximately 60 percent of stillbirths are unexplained. Those cases that do have determined causes usually fall into one of the following key categories:

Chromosomal Abnormalities

Chromosomal anomalies are responsible for about 60 percent of miscarriages and are less frequently the cause of stillbirth. The March of Dimes states, “Between five and 10 percent of stillborn babies have abnormalities involving their chromosomes, the tiny thread-like structures in each cell that carry our genes.” In contrast, only two to three percent of liveborn infants have chromosomal abnormalities, write Douglas and Dr. Sussman.

Maternal Health Problems

“Certain types of medical conditions can increase a pregnant woman’s chances of experiencing stillbirth,” write Douglas and Dr. Sussman. The fact that a woman begins a pregnancy with one of the following problems—or develops it while pregnant—in no way means that she won’t have a healthy baby. It simply necessitates careful monitoring of the pregnancy.

The following maternal health problems are most often associated with stillbirth:

  • Diabetes (Type I, Type II, and gestational)
  • Epilepsy
  • Hypertension (high blood pressure)
  • Heart disease
  • Kidney/Liver/Lung disease
  • Parathyroid disease
  • Sickle-cell disease
  • Lupus
  • Preeclampsia
  • Blood clotting disorders

Again, having one of these conditions does not mean that you will have a stillborn baby or that, if you experience a stillbirth, the pregnancy loss was definitely caused by that condition. However, a pathologist and your obstetrician will work to determine whether the health problem precipitated the stillbirth.


Many different infections can cross from the mother to the unborn baby through the placenta. Some of these infections include Fifth Disease (a common infection in children), listeriosis, rubella, toxoplasmosis (contracted by handling raw or undercooked meat, or contact with cat feces), and sexually transmitted diseases, including chlamydia, syphilis, and herpes.

Problems with the Placenta

Starting at the twelfth week of pregnancy, the placenta is the source of a developing baby’s nutrients, antibodies, and oxygen. It also “returns waste products to the mother for disposal and produces hormones that help to maintain the pregnancy,” write Douglas and Dr. Sussman.

It is estimated that about 15 to 25 percent of stillbirths and neonatal deaths (deaths that occur in the first 28 days of life after birth) are caused by placental problems.

There are three main types of placental problems:

  • Placental abruption is when the placenta partially or completely separates from the wall of the uterus. This is caused by bleeding between the placenta and the uterine wall. Abruption occurs in one in 150 pregnancies.
  • Placental previa is diagnosed when the placenta implants very low in the uterus, covering or partially covering the cervix. As the uterus stretches to accommodate the growing baby, bleeding occurs and, unless caught by the physician, causes fetal death.

Problems with the Uterus

The uterus is a baby’s home for eight and one-half months, but sometimes, a problem occurs with the uterus that put the baby in danger. One of the most common causes of stillbirth relating to the uterus is incompetent cervix.

The cervix is the tight ring at the base of the uterus; in some women, the cervix opens prematurely. According to Douglas and Dr. Sussman, the “peak period for losses due to an incompetent cervix is sixteen to twenty-four weeks of pregnancy,” and this problem causes approximately 15 percent of second-trimester deaths.

Umbilical Cord Problems

The umbilical cord is the direct support line between the mother and her baby. When a problem occurs with the cord, the baby is put at risk. Thankfully, many babies born with cord complications—such as knots, a cord around the neck or limbs, or other problems—are born healthy and screaming. However, according to a November 2004 Pregnancy Institute report, of the about 4 million births per year in the United States, about 4,000 babies are stillborn due to umbilical cord accidents (UCA).

Dr. Jason Collins, MD, is the president of the non-profit Pregnancy Institute in Louisiana. He is in charge of the Perinatal Umbilical Cord Project (PUCP). “UCAs represent 20 percent of all stillbirths,” says Dr. Collins. “As a cause of death it is two to four deaths per 1,000 live births. What is notable about these statistics is stillbirth due to umbilical cord accidents is more frequent than death due to maternal hypertension or gestational diabetes, which combined are responsible for 1 to 2 deaths per 1,000 live births.”

According to Dr. Collins, there are 25 different umbilical cord pathologies, and all are detectable on ultrasound. The problem is that there is not an established protocol for establishing these pathologies prenatally. Women who are not labeled high-risk are not screened for umbilical cord problems. Dr. Collins’ goal with the PUCP is to “demonstrate that it is possible to identify UCA and manage it to prevent stillbirths.”

Hope in Research

Whether parents who have experienced stillbirth were given a reason for their babies’ deaths or not, many turn to scientific research for hope. They seek a promise that such a tragedy won’t happen again during a subsequent pregnancy, and that this mystery will be further explored so that the next generation will see stillbirth defeated.

Dr. Donald Dudley, MD, is the director of the National Center of Excellence in Women’s Health and a professor in the Department of Obstetrics and Gynecology at the University of Texas Health Sciences Center at San Antonio. He says that when a baby is stillborn, the doctor feels a sense of failure and loss. “We are trained to do what we can to help women achieve a successful pregnancy with a happy outcome for parents and baby,” says Dr. Dudley. “Having a stillbirth is not what we want.”

That feeling of loss has led Dr. Dudley to participate in the Stillbirth Collaborative Research Network (SCRN), one of the largest studies evaluating the causes of stillbirth with the most modern testing possible. “The study will be performed with contemporary control patients, that is, women who have live births,” shares Dr. Dudley.

The goal of the study, which is funded by the NICHD, is to develop a “rational diagnostic approach to women who suffer stillbirth so we can tell them why their stillbirth occurred,” Dr. Dudley adds.

Tests to Determine the Cause of Stillbirth

Although it’s hard for parents of a baby who was just stillborn to accept, an autopsy is a vitally important test. “The pathology doctors will evaluate all the organs of the baby to determine if any are abnormal,” explains Dr. Dudley. “Often, they can determine a distinct diagnosis of a specific disease or syndrome that can lead directly to the cause of the stillbirth and provide information on the risk to future pregnancies.”

Another important test is a culture and examination of the placenta, according to Douglas and Dr. Sussman: “the placenta should be examined for signs of infection and/or abnormalities that might have caused the stillbirth.”

Simple blood tests should be performed on the mother to test for possible causes of the stillbirth, including:

  • Diabetes
  • Syphilis
  • Toxoplasmosis
  • Human prvovirus
  • Cocaine
  • Feto-maternal hemorrhage
  • Antibody problems

There is still some controversy over whether the physician should do a genetic amniocentesis, in which cells from the amniotic fluid are obtained before the baby is delivered. Douglas and Dr. Sussman write that these cells can offer valuable clues for up to two weeks after the death of the fetus. In contrast, they say, fetal cells often can’t provide such useful evidence.

Dr. Dudley, however, does not include this test with the battery he and his researchers are performing with the SCRN study. “Research has not conclusively shown that this is any more useful than the tests on the placenta and the fetus,” he says.

As sad and as difficult as it is for parents to think through these questions about testing, it is a very important part of healing. Currently, many parents must somehow accept that they’ll never know why their babies died, many during seemingly uneventful pregnancies. However, studies have shown that the cause of fetal death can be determined in 80 to 90 percent of cases if all the above outlined tests (blood and urine tests, autopsy, cord examination, and placental examination) are performed. That’s substantially better than the traditionally accepted 60 percent rate of unexplained stillbirths.

Knowing how or why a baby was stillborn doesn’t bring the baby back, but it does provide a measure of understanding and closure. It also can offer the couple and their physician important information about how to manage a subsequent pregnancy. There is hope that, just as we’ve learned more about SIDS and informed the public, stillbirth rates will fall just as SIDS rates have plummeted over the past decade.

“Stillbirth is a relatively common important public health issue because it reflects on the quality and quantity of prenatal case and on the general health of a population, and it always tragic,” says Dr. Dudley. Many parents are hoping and praying that research done both on a personal and a large-scale level will provide valuable answers to understanding this silent killer.

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