Risk Factors of Preterm Birth

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

While it is important to track these risk factors in every pregnancy, up to half of women who deliver prematurely have no known risk factors.1

male doctor using stethoscope on pregnant women's belly

Known Risk Factors

Medical risk factors for preterm birth:*
  • Prior miscarriage
  • Pregnancy with multiples
  • Family history of premature birth (sister, mother, or grandmother)
  • Maternal age (17 or younger, 35 or older)
  • Problems with uterus, placenta, or cervix (including short cervix length)
  • Pregnant through in vitro fertilization (IVF)
  • Maternal weight (underweight or overweight before pregnancy)

*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:*
  • High stress levels
  • Smoking
  • Alcohol use

Predicting Preterm Birth Risk: Standard Methods

Although breakthroughs in obstetrics and neonatal care have vastly improved the odds of healthy survival for mothers and infants, methods for assessing the risk for spontaneous preterm birth have not advanced as quickly. Until recently the primary tools for assessing this risk have include the history of preterm birth and measurements of cervical length. Even with these tools, most cases of premature birth were “hiding in plain sight,” not apparent until too late to change clinical course.

Prior History of Preterm Birth

In clinical studies, a history of previous preterm birth identified 11% of future preterm births.2,3

Short Cervical Length

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, cervical length screening detects only an additional 6% of singleton pregnancies that deliver prematurely. 4,5

Predicting Preterm Birth Risk: A New Approach

Improved spontaneous preterm birth risk prediction means a better chance for physicians and patients to work together to make clinical decisions to extend gestation time and provide better outcomes.

Recently, scientists discovered that key proteins, measured in the blood of pregnant women, were powerful predictors of a higher risk of sPTB. 

Based on this discovery, Sera developed the PreTRM Test, the first broadly clinically validated blood test to provide early risk stratification for spontaneous preterm birth in singleton pregnancies in women with no known risk factors. The PreTRM Test provides early, accurate, individualized risk information to help patients and physicians make more informed healthcare decisions.

Contact Us

Contact us for more information about preterm birth and the PreTRM Test.

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References

  1. Iams, JD, et al. Prevention of preterm parturition. N Engl J Med. 2014;370:254-61.
  2. Petrini JR, et al. Estimated effect of 17 alpha-hydroxyprogesterone caproate on preterm birth in the United States. Obstet Gynecol. 2005;105:267-72.
  3. Martin JA, et al. Births: Final Data for 2002. Natl Vital Stat Rep. 2003; 52(10):1-113.
  4. 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;38:18-31.
  5.  Martin JA, et al. Births: Final Data for 2009. Natl Vital Stat Rep. 2011; 60(1):1-70.