What are the risk factors for stillbirth?

Stillbirth can happen in any pregnancy. Even after a thorough investigation, a probable or possible cause of stillbirth may not be found.1

Even though there are certain risk factors for stillbirth, most individual stillbirths in the United States are not linked to any known risk factors that the woman has at the time she learns she is pregnant.2

Risks for Stillbirth in High-Income Countries

Studies have found many factors that increase risk for stillbirths in the United States and other high-income countries.

There are several types of factors, such as:2,3,4

Maternal Characteristics

  • Low socioeconomic status
  • Older age (older than age 35)
  • Smoking tobacco or marijuana during or just before pregnancy, or exposure to secondhand smoke during pregnancy
  • Using illegal drugs before or during pregnancy

Maternal Medical Conditions

  • Being overweight or obese
  • Diabetes before pregnancy
  • High blood pressure before pregnancy

Maternal Reproductive History

  • Never having given birth before
  • Previous stillbirth or small for gestational age infant
  • Pregnancy with twins, triplets, or other multiples
  • Assisted reproductive technology

Fetal Characteristics

  • Small size in the fetus, given its age (sometimes called small for gestational age [SGA]). SGA can sometimes be due to growth restriction, a risky condition in which there is a problem with the pregnancy that prevents the fetus from growing as well as it could otherwise.

Risks for Stillbirth in Resource-Limited Countries

In developing countries, lack of access to obstetrical care contributes to high stillbirth rates. Most stillbirths in the developing world result from long and difficult labor, preeclampsia, and infections.5

A study conducted by the Global Network for Women’s and Children’s Health Research (funded by NICHD and the Bill and Melinda Gates Foundation) showed that providing basic newborn care training to birth attendants in low-income countries makes the stillbirth rate plummet.

As a result of the intervention, the rate of stillbirths dropped from 1 per every 43 deliveries to about 1 per 63 deliveries. The researchers believed this improvement was due to an increase in babies being resuscitated if they were not breathing at birth—a common problem that an untrained birth attendant might classify as a stillbirth. However, trained birth attendants can treat this problem using resuscitation techniques, including rubbing the newborn’s back.6,7

Citations

  1. The Stillbirth Collaborative Research Network Writing Group. (2011). Causes of death among stillbirths. Journal of the American Medical Association, 306(22), 2459–2468.
  2. Stillbirth Collaborative Research Network Writing Group. (2011). Association between stillbirth and risk factors known at pregnancy confirmation. Journal of the American Medical Association, 306(22), 2469–2479.
  3. Flenady, V., Koopmans, L., Middleton, P., Frøen, J. F., Smith, G. C., et al. (2011). Major risk factors for stillbirth in high-income countries: a systematic review and meta-analysis. The Lancet, 377(9774), 1331–1340.
  4. Varner, M. W., Silver, R. M., Rowland Hogue, C. J., Willinger, M., Parker, C. B., Thorsten, V. R., et al; Stillbirth Collaborative Research Network. (2014). Association between stillbirth and illicit drug use and smoking during pregnancy. Obstetrics & Gynecology, 123(1), 113–125.
  5. McClure, E. M., Nalubamba-Phiri, M., & Goldenberg, R. L. (2006). Stillbirth in developing countries. International Journal of Gynaecology and Obstetrics, 94(2), 82–90.
  6. Carlo, W. A., Goudar, S. S., Jehan, I., Chomba, E., Tshefu, A., Garces, A., … & First Breath Study Group. (2010). Newborn-care training and perinatal mortality in developing countries. New England Journal of Medicine, 362(7), 614–623. doi: 10.1056/NEJMsa0806033.
  7. NICHD. (2010). Stillbirths drop dramatically after newborn-care training in developing countries. Retrieved July 31, 2013, from http://www.nichd.nih.gov/news/releases/Pages/021810-stillbirths-dropped-dramatically.aspx
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