Fetal Mortality

Narrative

Fetal mortality is defined as the death of a fetus before birth, regardless of gestational age. Based on survey data, more than a million fetal losses are estimated to occur annually in the United States, most of which are early fetal losses, which are also called miscarriages.1 Only fetal deaths at 20 or more weeks’ gestation—often called stillbirths— are generally reported by states in the National Vital Statistics System.2 In 2012, there were 24,073 fetal deaths at 20 or more weeks’ gestation, for a rate of 6.05 fetal deaths per 1,000 live births plus fetal deaths. The number of fetal deaths is as high as the number of infant deaths (24,001 in 2011), which doubles the health and emotional toll when fetal and infant mortality are considered together. Causes of fetal death are similar to causes of infant death in the first month of life, including placental problems and preterm labor, birth defects, infection, umbilical cord accidents, and chronic conditions such as hypertension and diabetes.3, 4

Fetal mortality rates at 20 weeks or more have declined from 7.49 to 6.05 per 1,000 between 1990 and 2006 (Figure 1). Most of this decline is attributed to reductions in fetal mortality at 28 weeks or more gestation, which declined from 4.30 to 2.97 per 1,000 between 1990 and 2006. However, there has been no change in fetal mortality from 2006 to 2012, a period during which infant mortality declined (more on infant mortality).

Fetal Mortality Rates

Figure 1 Source

As with infant mortality, there are large differences in fetal mortality rates by race and ethnicity. In 2012, fetal mortality rates at 20 or more weeks’ gestation were more than twice as high among non-Hispanic Black women as among non-Hispanic White women (10.67 versus 4.91 per 1,000; Figure 2). Relative to non-Hispanic Whites, fetal mortality rates were also higher for American Indian/Alaska Native and Puerto Rican women (6.64 and 6.62 per 1,000, respectively).

Fetal Mortality Rates by Race

Figure 2 Source

Fetal mortality also varies by maternal age, with higher rates observed among younger and older women. In 2012, fetal mortality was highest among women aged 35 years and older (7.65 per 1,000), followed by those under 20 years of age (6.90 per 1,000). Women aged 25–34 years had the lowest fetal mortality rates, at about 5.50 per 1,000.

Prevention opportunities that may reduce the risk of stillbirth include avoiding smoking, substance use, and certain prescription and over-the-counter medications; maintaining a healthy weight; and preventing and managing chronic conditions before and during pregnancy through preconception and prenatal care.5 Careful clinical monitoring for women with high-risk conditions or vaginal bleeding may also avert fetal deaths, as early cesarean delivery can be lifesaving when medically necessary.

Data Sources

Figure 1. MacDorman MF, Kirmeyer SE, Wilson EC. Fetal and perinatal mortality, United States, 2006. National Vital Statistics Reports, vol. 60, no. 8. Hyattsville, MD: National Center for Health Statistics; 2012.
U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics. User Guide to the 2012 Fetal Death Public Use File. Vital Statistics Data Available Online. Accessed October 7, 2014.
Martin JA, Hamilton BE, Osterman JK, et al. Births: final data for 2012. National Vital Statistics Reports, vol. 62, no. 9. Hyattsville, MD: National Center for Health Statistics; 2013.

Figure 2. MacDorman MF, Kirmeyer SE, Wilson EC. Fetal and perinatal mortality, United States, 2006. National Vital Statistics Reports, vol. 60, no. 8. Hyattsville, MD: National Center for Health Statistics; 2012.
Martin JA, Hamilton BE, Osterman JK, et al. Births: final data for 2012. National Vital Statistics Reports, vol. 62, no. 9. Hyattsville, MD: National Center for Health Statistics; 2013.

Endnotes

1 Ventura SJ, Curtin SC, Abma JC, Henshaw SK. Estimated pregnancy rates and rates of pregnancy outcomes for the United States, 1990–2008. National Vital Statistics Reports, vol. 60, no. 7. Hyattsville, MD: National Center for Health Statistics; 2012.

2 MacDorman MF, Kirmeyer SE, Wilson EC. Fetal and perinatal mortality, United States, 2006. National Vital Statistics Reports, vol. 60, no. 8. Hyattsville, MD: National Center for Health Statistics; 2012.

3 Stillbirth Collaborative Research Network Writing Group. Causes of death among stillbirths. Journal of the American Medical Association. December 14, 2011;306(22):2459–2468.

4 March of Dimes Foundation. Stillbirth. Accessed September 24, 2014.

5 March of Dimes Foundation. Stillbirth. Accessed September 24, 2014.

Data

Statistical Significance Test

Calculate the difference between two estimates:

Calculated Z-Test Result 0.9567433 Not statistically significant

We follow statistical conventions in defining a significant difference by a p-value less than 0.05 where there is a less than 5% probability of observing a difference of that magnitude or greater by chance alone if there were really no difference between estimates. The 95% confidence interval includes a plausible range of values for the observed difference; 95% of random samples would include the true difference with fewer than 5% of random samples failing to capture the true difference.

This website allows comparisons between two estimates using the independent z-test for differences in rates or proportions. This test is appropriate for comparing independent populations across years (e.g., 2011 versus 2012) or subgroups (e.g., Male versus Female) on corresponding measures. To the extent possible, the functionality of this application has limited estimate comparisons based on appropriate use of the independent z-test. However, some tables present subgroup categories within broader categories that will allow comparisons between non-independent populations (e.g., low birth weight and very low birth weight). Users should exercise caution when interpreting these test results, which will frequently overstate statistical significance.

For some tables, the website does not allow for comparisons between two estimates, even though the data represent independent populations. Generally, this is because the standard errors were not publicly available at the time this website was created.

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