Screening for stillbirth risk: Who benefits from additional testing?
January 18, 2022
In the U.S., approximately 1 in 160 pregnancies ends in stillbirth – pregnancy loss at or after 20 weeks’ gestation. Maternal COVID-19 infections have increased stillbirth rates in the last couple of years, drawing attention to the difficulty of standardizing risk assessment protocols due to the uniqueness of each pregnancy.
However, several risk factors for stillbirth can be grouped into three categories:
- Fetal: Genetic disorders, multiple gestations (twins, triplets, etc.), fetuses that develop after fertility treatments
- Maternal: High-risk health conditions and behaviors, including diabetes, high blood pressure, obesity, and alcohol or drug use during pregnancy
- Placental: Abnormal placenta development that prevents proper fetal growth
Based on these factors, in June 2021 the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) released updated recommendations for reducing stillbirth risk.
The joint statement provides guidelines about the timing and frequency of antenatal fetal surveillance – how often and for whom providers should conduct specific tests during pregnancy to assess the risk of stillbirth and intervene with early delivery, if necessary.
In a world of diverse medical opinions, having one set of recommendations endorsed by the country’s two biggest Ob/Gyn professional associations will be beneficial. Group practice providers and pregnant patients can refer to the guidelines when weighing the risks of stillbirth and early delivery against the benefits of giving a baby more time to develop in utero.
But as noted in the statement, the guidelines are not absolute and should be customized to each patient. An open, collaborative discussion about risks should precede any test, and patients should feel empowered to ask their doctors why certain tests are being performed – or why not.
Related reading: 4 pregnancy blood tests not all patients need
Understanding fetal ultrasounds
Dr. Robyn Horsager describes some of the movements of a baby that can be seen on ultrasound during the various stages of pregnancy, including tiny movements at nine weeks, big kicks at 20 weeks, and when a baby has hiccups in the womb.
2 common fetal assessment tests
Fetal movement varies, but it is a strong indicator of your baby’s well-being – especially if movement decreases toward the end of pregnancy. If we’re concerned about your baby’s overall health, we’ll monitor its movement, as well as other critical functions, by performing one of two tests:
- Electronic fetal monitoring: This test records the fetal heart rate pattern. An abnormal pattern can mean your baby is under some type of in-utero stress. We usually combine this test with an ultrasound to assess the amniotic fluid volume. Too little amniotic fluid can indicate a problem with placental function and increase the risk of birth complications.
- Biophysical profile: This test uses an ultrasound to evaluate fetal breathing, movement, and muscle tone, as well as the amount of amniotic fluid. Each of these areas gets a score of 0-2, with a total score of 8 possible. It can be combined with electronic fetal monitoring if necessary. If your total score is less than 6, we’ll likely pursue further assessment of how your baby is doing.
When and how often we perform these tests varies for each patient, but more consistency has the potential to help reduce stillbirth rates.
Related reading: Understanding how 4 abnormal ultrasound findings relate to miscarriage risk
Suggested testing frequency
Although ACOG and SMFM recommend individualizing tests and frequency rates, the 2021 antenatal fetal surveillance guidelines provide a solid starting point for providers and patients concerned about stillbirth risk.
Having one or more of these conditions does not mean you will experience a stillbirth. However, we want to keep a closer eye on you and your baby to increase the likelihood of a healthy delivery. Following are the general guidelines by stillbirth risk category.
Fetal risks
Conditions that warrant surveillance:
- Decreased fetal movement: Test once at diagnosis.
- Fetal growth restriction: Test at diagnosis up to twice weekly or require inpatient management, depending on the risk severity.
- Multiple gestation: At minimum, weekly testing starts at diagnosis. Frequency should be tailored to the patient based on other health complications.
Maternal risks
Conditions that warrant surveillance:
- Age over 35: Individualize testing based on other pregnancy complications.
- Chronic hypertension: Test at diagnosis or week 32 of pregnancy at least weekly, depending on how well your blood pressure is controlled.
- Diabetes: Test at week 32 of pregnancy once or twice weekly, depending on how what your blood sugar measurements look like..
- Preeclampsia: Test at diagnosis twice weekly or daily, depending on risk and severity.
- Systemic lupus erythematosus: Test by week 32 of pregnancy up to twice weekly, depending on the patient.
Placental risks
Conditions that warrant surveillance:
- Isolated oligohydramnios (amniotic fluid volume) less than 2 cm: Test once or twice weekly at diagnosis.
- Single umbilical artery (umbilical cord has only one artery instead of two): Test weekly starting at week 36 of pregnancy.
Related reading: Helping you understand scary (but often harmless) pregnancy ultrasound findings [HE2]
Avoid over-testing
From changing your diet to getting vaccinated against COVID-19, plenty of precautions can help protect fetal health. But being overly cautious has risks, too.
The more tests you have, the more likely you are to get false-positive results, which can increase your anxiety and the risk of preterm delivery. Babies born prematurely can have breathing, blood, immune system, and gastrointestinal complications as well as long-term behavioral and chronic health issues.
To avoid getting too many tests, ask your doctor why they’re requesting certain tests.
Open, honest communication with your provider is critical during pregnancy. The healthiest pregnancy decisions are made when patients and providers are on the same page.
Related reading: 6 pregnancy ultrasound exams you might not need
To visit with an Ob/Gyn about your risk of pregnancy complications, call 214-645-8300 or request an appointment online.
