Limitations of Traditional Preterm Birth Screening Methods

Identifying women at higher risk for preterm birth is a critical first step to addressing an early delivery’s health impacts. Until now, risk prediction tools have been limited, with only a small percentage of singleton pregnancies identified to be at risk for a spontaneous preterm birth.

pregnant lady at maternity clinic

Traditional Methods Alone Fail to Detect 80% of Spontaneous Preterm Births

Prior preterm birth history identifies 11% of singleton pregnancies that deliver prematurely.1,2

Patients with a prior spontaneous preterm birth history carry a 2.5-fold increase in risk compared to those with no prior spontaneous preterm delivery.3 This risk factor identifies 11% of singleton pregnancies that deliver prematurely. A major limitation of this risk factor is that four out of 10 births occur in first-time mothers without obstetrical history, so physicians  are unable to rely on this information.4

Cervical length screening detects an additional 6% of singleton pregnancies that deliver prematurely.5,6

The use of vaginal ultrasound to measure cervical length during pregnancy is used as a screening measure to assess the risk of preterm birth. However, the incidence of a short cervix is very low and this screening method detects only an additional 6% of singleton pregnancies that deliver prematurely.

Traditional methods alone fail to detect 80% of spontaneous preterm births

Cervical length alone is not an adequate tool to identify women who go on to deliver prematurely. The data behind the PreTRM® clinical validation studies (PAPR and TREETOP) highlight a real opportunity to provide a tool to clinicians to better help identify and stratify patients at increased risk of delivering prematurely who otherwise have no known risk factors.

Dr. Michael Foley, MD
Professor and Chair, University of Arizona College of Medicine OB/GYN Department
Physician Executive, Women’s Service Line Banner Health
Past President, Society of Maternal-fetal Medicine
Incoming Chief Medical Officer, Sera Prognostics

Other Risk Factors for Preterm Birth

The specific causes of all spontaneous preterm births are not fully understood. However, there are several known risk factors.

Medical risk factors for preterm birth examples*

  • Prior miscarriage
  • Pregnancy with multiples
  • Family history of premature birth (sister, mother, or grandmother)
  • Short inter-pregnancy interval
  • Maternal age (17 or younger, 35 or older)
  • Prior cervical procedures (such as LEEP or cone biopsy)
  • Diabetes
  • High blood pressure
  • Pregnant through in vitro fertilization (IVF)
  • Sleep disorders (such as insomnia or sleep apnea)
  • Certain infections (such as bacterial vaginosis, chlamydia, gonorrhea)
  • Maternal weight (BMI <19, or pre-pregnancy weight <50kgs [<120lbs] )
  • Vaginal bleeding (1st and 2nd trimester, placenta previa, abruption)

*This is not a comprehensive list or a recommendation of all risk factors that clinicians should use to determine a patient’s risk for preterm birth.

Lifestyle risk factors for preterm birth examples*

  • Heavy alcohol consumption
  • Low socioeconomic status
  • Environmental pollution
  • High stress levels
  • Smoking
  • Drug use

*This is not a comprehensive list or a recommendation of all risk factors that clinicians should use to determine a patient’s risk for preterm birth.

Leveraging Biomarkers From the Blood for a Comprehensive Risk Assessment

Advances in science now allow for earlier prediction, far greater accuracy, and the individualized insight to improve outcomes. The PreTRM Test assesses protein biomarkers in the maternal serum to identify asymptomatic singleton pregnancies that are at higher risk for a premature delivery. Greater than four times as many patients at higher can be identified using a comprehensive risk assessment comprised of the PreTRM Test and traditional screening methods than by using traditional methods alone.7

Clinical Studies

Learn more about the PAPR study

The Science Behind the Test

Explore the science behind the two proteins assessed by the PreTRM Test.

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  1. Petrini JR, et al. Estimated effect of 17 alpha-hydroxyprogesterone caproate on preterm birth in the United States. Obstet Gynecol. 2005;105:267-72.
  2. Martin JA, et al. Births: Final Data for 2002. Natl Vital Stat Rep. 2003;52(10):1-113.
  3. Mercer et al. The Preterm Prediction study: Effect of gestational age and cause of preterm birth on subsequent obstetric outcome. Am J Obstet Gynecol. 1999;181(5 Pt 1):1216-21.
  4. Martin JA, et al. National Vital Statistics Report. Births: Final Data for 2018. Natl Vital Stat Rep. 2019;68(13):1-47.
  5. Hassan SS, et al. Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial. Ultrasound Obstet Gynecol. 2011;38(1):18-31.
  6. Martin JA, et al. Births: Final Data for 2009. Natl Vital Stat Rep. 2011;60(1):1-70.
  7. Saade GR, et al. Development and validation of a spontaneous preterm delivery predictor in asymptomatic women. Am J Obstet Gynecol. 2016;214(5):633.e1-24.