Births

There are approximately 4 million births per year in the United States. The average age of a mother giving birth has risen to 25 years in the United States and to 29 years in the United Kingdom (average age at first child, 27 years). There has been a steady rise in the birth rate for women in their thirties and forties. The teenage birth rate has declined considerably, with a 10% reduction between 2010 and 2011 in those teenagers aged 15 to 19. Overall there has been a 38% decline in births to teenagers since 1991.⁷

Maternal Mortality

The huge reduction in maternal mortality is one of the most dramatic improvements in health outcomes in high-income countries. In the United States, maternal mortality declined from 582 per 100,000 live births in 1936 to 11.5 per 100,000 in 1990. This is because of reduced mortality from puerperal sepsis following the development of antibiotics, improved obstetric care, availability of blood and blood products, and better maternal health, including fewer pregnancies per woman. The death of a woman during pregnancy, at delivery, or soon after delivery is a tragedy for her family and for society as a whole. Approximately 650 women die in the peripartum period in the United States every year. The Centers for Disease Control (CDC) instituted a Pregnancy Mortality Surveillance System in 1987. Since this system was instituted, there has been a steady rise in the number of pregnancy-related deaths, with a peak in 2003 of 16.8 deaths per 100,000 live births. In 2008, the rate was 15.5 deaths per 100,000 live births.4,5 The reasons for the increased mortalities are unclear. Some cite improved data capture or increased linkage of electronic datasets. However, it is well recognized that there has been an increase in the number of pregnant women with chronic health conditions such as obesity, hypertension, diabetes, and chronic heart disease.^2,10,11 These conditions place a pregnant woman at a higher risk of adverse outcomes.⁴ It is a national tragedy that African-American mothers have a threefold to fourfold higher risk of pregnancy-related deaths. The top five causes of all maternal, pregnancy-related deaths between 2006 and 2008 were: cardiovascular diseases (14.6%), cardiomyopathy (12.4%), noncardiovascular disease (11.9%), hemorrhage (11.5%), and sepsis (11.1%).⁴

Infant Mortality

Infant mortality is a critical measure of the health and welfare of a population. In 2011, 23,910 infants died before reaching age 1 year, resulting in an infant mortality rate of 6.05 deaths per 1000 live births.⁷ Rates of infant death in the United States have been declining steadily for at least 40 years and reached a record low in 2002 (Figure 2-1). Despite the constant improvement in national infant mortality rates, the United States ranks only 25th in the world in infant mortality, well behind Sweden, Japan, Singapore, and Hong Kong. Six countries had an infant mortality rate less than half the US rate. Recent analyses indicate that a major trend toward increased care for infants less than 500 g birth weight has contributed to the disparity.¹²

The five leading causes of infant death in 2011 were congenital malformations (20.8%), disorders of short gestation or low birth weight (17.2%), sudden infant death syndrome (7.2%), newborn affected by maternal complication of pregnancy (6.6%), and unintentional injuries (4.6%).

There was a substantial and persistent difference between African-American and white infants in the risk of low birth weight (LBW) and preterm delivery. African-American women are 2.4 times more likely to have an infant with LBW than white women. The higher LBW rate among African-American women has been observed for more than 20 years. African-American infants are more likely to die of preventable causes than white infants. In addition, African-American infants have significantly higher rates of mortality for every cause of infant death except congenital anomalies and sudden infant death syndrome.

Decades of research about the disparities in LBW rates and infant mortality between African-American and white infants have been unable to explain the racial disparities in birth outcomes. Scientists have studied the impact of education, maternal age, vaginal infection, exposure to cigarette smoke, use of alcohol, stress, socioeconomic status, and many other risk factors. None of these factors explains the racial disparities in death or LBW rates.

Conditions that make the uterus unable to retain the fetus include interference with the course of pregnancy, premature separation of the placenta, or a stimulus to produce uterine contractions before term; these conditions are generally associated with preterm infants with an appropriate weight for gestational age. Medical conditions that interfere with the circulation and efficiency of the placenta, the development or growth of the fetus, or the general health and nutrition of the mother are associated with infants who are small for gestational age.

Infant deaths are divided into two categories according to age: neonatal (deaths of infants <28 days old) and postneonatal (deaths of infants between the ages of 28 days and 1 year).

Neonatal deaths are generally attributable to factors that occur during pregnancy, such as congenital malformations, low birth weight, maternal toxic exposures (smoking or other forms of drug abuse), and lack of appropriate medical care. In contrast, postneonatal deaths are generally associated with the infant’s environmental circumstances, such as poverty, which often results in inadequate food, housing, sanitation, and medical care. In 2011, the neonatal mortality rate was 4.04 deaths per 1000 live births, and the postneonatal mortality rate was 2.01 deaths per 1000 live births. Overall, the infant mortality rate in the United States steadily declined between 2005 and 2011 (Figure 2-2).⁷

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