Causes of infant mortality, or direct causes of death, differ from contributions to the IMR, as contributing factors raise the risk of death, but do not directly cause death. Environmental and social barriers that prevent access to basic medical resources contribute to an increased infant mortality rate, 86% of infant deaths are caused by
infections,
premature births, complications during delivery, perinatal
asphyxia, and birth injuries. Many of these common causes are preventable with low-cost measures. In the United States, a primary source of infant mortality risk is infant birth weight, with lower birth weights increasing the risk; the causes of low birth weight include socioeconomic, psychological, behavioral, and environmental factors.
Main causes There are three main leading causes of infant mortality: conditions related to
preterm birth,
congenital anomalies, and
SIDS (sudden infant death syndrome). In North Carolina between 1980 and 1984, 37.5% of infant deaths were due to prematurity, congenital anomalies accounted for 17.4% and SIDS accounted for 12.9%. A lower gestational age increases the risk of infant mortality. Between 1990 and 2010 prematurity was the second leading cause of worldwide mortality for neonates and children under the age of five. Low-income countries also have limited resources to care for the needs of preterm infants, which increases the risk of infant mortality. The survival rate in these countries for infants born before 28 weeks of gestation is 10%, compared with a 90% survival rate in high-income countries. In the United States, the period from 1980 to 2000 saw a decrease in the total number of infant mortality cases, despite a significant increase in premature births. Both spontaneous factors are viewed to be a result of similar causes; hence, two main classifications remain: spontaneous and medically induced causes. The risk of spontaneous PTB increases with "extremes of maternal age (both young and old), short inter-pregnancy intervals, multiple gestations, assisted reproductive technology, prior PTB, family history, substance abuse, cigarette use, low maternal socioeconomic status, late or no prenatal care, low maternal prepregnancy weight,
bacterial vaginosis,
periodontal disease, and poor pregnancy weight gain." Medically induced preterm birth is often conducted when continuing pregnancy poses significant risks to the pregnant parent or fetus; the most common causes include
preeclampsia, diabetes, maternal medical conditions,
fetal distress, or developmental problems. The main body systems affected include the respiratory system, which may result in
pulmonary hypoplasia,
respiratory distress syndrome,
bronchopulmonary dysplasia (a chronic lung disease), and
apnea. Additionally, understanding the risks associated with different gestational ages is a helpful determiner of
Gestational age-specific mortality.
Sudden infant death syndrome (SIDS) Sudden infant death syndrome (SIDS) is defined as the sudden death of an infant less than one year of age with no cause detected after a thorough investigation. SIDS is more common in Western countries. The
United States Centers for Disease Control and Prevention report SIDS to be the leading cause of death in infants aged one month to one year of life. Even though researchers are not sure what causes SIDS, they have found that putting babies to sleep on their backs, instead of their stomachs, lowers the risk. Campaigns like
Back to Sleep have used this research to lower the SIDS death rate by 50%. Though the exact cause is unknown, the "triple-risk model" presents three factors that together may contribute to SIDS: smoking while pregnant, the age of the infant, and stress from conditions such as prone sleeping,
co-sleeping, overheating, and covering of the face or head. In the United States, approximately 3,500 infant deaths are sleep-related, a category that includes SIDS. To reduce sleep-related infant deaths, the American Academy of Pediatrics recommends providing infants with safe-sleeping environments, breastfeeding, and immunizing according to the recommended
immunization schedule. They recommend against the use of a
pacifier and recommend avoiding exposure to smoke, alcohol, and illicit drugs during and after pregnancy. Congenital malformations have had a significant impact on infant mortality, but malnutrition and infectious diseases remain the main causes of death in less developed countries. For example, in the Caribbean and Latin America in the 1980s, congenital malformations only accounted for 5% of infant deaths, while malnutrition and infectious diseases accounted for 7% to 27% of infant deaths. In more developed countries, such as the United States, there was a rise in infant deaths due to congenital malformations, mostly heart and central nervous system problems. In the 20th century, there was a decrease in the number of infant deaths from heart conditions, from 1979 to 1997, there was a 39% decline.
Medicine and biology Causes of infant mortality and deaths that are related to medical conditions include: low birth weight,
sudden infant death syndrome, malnutrition, congenital malformations, infectious diseases, and low income for health care, including
neglected tropical diseases. The American Academy of Pediatrics recommends that infants need multiple doses of vaccines such as
diphtheria–tetanus–acellular pertussis vaccine,
Haemophilus influenzae type b (Hib) vaccine,
hepatitis B (HepB) vaccine,
inactivated polio vaccine (IPV), and
pneumococcal vaccine (PCV). Research conducted by the
Institute of Medicine's
Immunization Safety Review Committee concluded that there is no relationship between these vaccines and the risk of SIDS in infants.
Low birth weight Low birth weight makes up 60–80% of the infant mortality rate in developing countries.
The New England Journal of Medicine stated that "The lowest mortality rates occur among infants weighing . For infants born weighing or less, the mortality rate rapidly increases with decreasing weight, and most of the infants weighing or less die. As compared with normal-birth-weight infants, those with low weight at birth are almost 40 times more likely to die in the neonatal period; for infants with very low weight at birth the relative risk of neonatal death is almost 200 times greater." The rate of low birth weights among African Americans remains twice as high as the rate for white people. Low birth weight, the leading cause of infant deaths, is preventable by effective programs to help prevent low birth weight are a combination of health care, education, the environment, and public policy. Preterm birth is the leading cause of newborn deaths worldwide. Even though America has a higher survival rate for premature infants, the percentage of Americans who deliver prematurely is comparable to those in developing countries. Reasons for this include
teenage pregnancy, an increase in pregnancy after the age of 35, an increase in the use of
in vitro fertilisation (which increases the risk of multiple births), obesity, and diabetes. Also, pregnant people who do not have access to health care are less likely to visit a doctor, therefore increasing their risk of delivering prematurely. It is especially prevalent during pregnancy and in infants and children under 5 who live in developing countries within the poorer regions of Africa, Asia, and Latin America. Children are especially vulnerable as they have yet to fully develop a strong
immune system and are dependent on their parents to provide the necessary food and nutritional intake. It is estimated that about 3.5 million children die each year as a result of childhood or maternal malnutrition, with
stunted growth, low body weight, and low birth weight accounting for about 2.2 million associated deaths. Socioeconomic and environmental factors contribute to malnutrition, as do gender, location, and cultural practices surrounding
breastfeeding. It is difficult to assess the most pressing factor as they can intertwine and vary among regions. Children suffering from malnutrition can become underweight, and experience stunting or
wasting. In Africa, the number of stunted children has risen, while Asia has the most children under 5 suffering from wasting. Inadequate nutrients adversely affect physical and cognitive development, increasing susceptibility to severe health problems. Micronutrient deficiency has been linked to
anemia, fatigue,
blindness,
goiter, poor brain development, and death. Malnutrition also decreases the immune system's ability to fight infections, resulting in higher rates of death from diseases such as malaria, respiratory disease, and diarrhea.
Folic acid during pregnancy is one way to combat iron deficiency. A few
public health measures used to lower levels of iron deficiency anemia include added iodine to salt or drinking water and including vitamin A and multivitamin supplements in the diet.
Infectious diseases Babies born in low- to middle-income countries in sub-Saharan Africa and southern Asia are at the highest risk of neonatal death. Bacterial infections of the bloodstream, lungs, and the brain's covering (
meningitis) are responsible for 25% of neonatal deaths worldwide. Newborns can acquire infections during birth from bacteria present in the birth canal, the person may not be aware of the infection, or they may have an untreated
pelvic inflammatory disease or a
sexually transmitted disease. These bacteria can also move up the vaginal canal into the amniotic sac surrounding the baby causing in utero transmission. Maternal blood-borne infection is another route of bacterial infection. Neonatal infection is more likely with the
premature rupture of the membranes (PROM) of the amniotic sac. Seven out of ten childhood deaths are due to infectious diseases like
acute respiratory infection,
diarrhea,
measles, and
malaria. Acute respiratory infections such as
pneumonia,
bronchitis, and
bronchiolitis account for 30% of childhood deaths; 95% of pneumonia cases occur in the developing world. Diarrhea is the second-largest cause of childhood mortality in the world, while malaria causes 11% of childhood deaths. Measles is the fifth-largest cause of childhood mortality.
Environmental The infant mortality rate is one measure of a nation's health and social conditions. Its causes are a composite of a number rates that each have their own separate relationships with each other and with various other social factors. As such, IMR can often be seen as an indicator to measure the level of socioeconomic disparity within a country. Organic
water pollution is a better indicator of infant mortality than health expenditures per capita. Water contaminated by animal waste houses various
pathogens including a host of
parasitic and
microbial infections. Areas of low
socioeconomic status are more prone to inadequate plumbing infrastructure and poorly maintained facilities. High infant mortality is exacerbated because newborns are a vulnerable subgroup that is affected by air pollution. Newborns who were born into these environments are no exception, and pregnant women exposed to greater air pollution on a daily basis should be closely watched by their doctors, including after the baby is born. Babies who live in areas with less air pollution have a greater chance of living until their first birthday, meaning babies who live in environments with more air pollution are at greater risk for infant mortality. Areas that have higher air pollution also have a greater chance of having a higher population density, higher crime rates, and lower income levels, all of which can lead to higher infant mortality rates. A key pollutant in infant mortality rates is
carbon monoxide. Carbon monoxide is a colorless, odorless gas that can kill, and is especially dangerous to infants because of their immature respiratory systems. Another major pollutant that can have detrimental effects on a fetus is second-hand smoke. Modern research in the United States into racial disparities in infant mortality suggests a link between
institutionalized racism and high rates of African American infant mortality. In synthesis of this research, it has been observed that "African American infant mortality remains elevated due to the social arrangements that exist between groups and the lifelong experiences responding to the resultant power dynamics of these arrangements." has made some headway in determining the reasons behind this, claiming black women in the US are more prone to psychological stress than women of other races. Stress is a leading factor in the start of labor, and therefore, high levels of stress during pregnancy could lead to premature births that have the potential to be fatal for the infant.
Early childhood trauma Early childhood trauma includes physical, sexual, and psychological abuse of a child from birth to five years old.
Trauma in early childhood has an extreme impact over the course of a lifetime and is a significant contributor to infant mortality. Developing organs are fragile, when an infant is shaken, beaten, strangled, or raped, the impact is exponentially more destructive than when the same abuse occurs to a fully developed body. Studies estimate that 1–2 per 100,000 U.S. children are fatally injured annually, and it is reasonable to assume that these statistics underrepresent actual mortality. Almost three-quarters (70.6%) of child fatalities in
FFY 2018 involved children younger than 3 years, and children younger than 1 year accounted for half (49.4%) of all fatalities. Family configuration, child gender, social isolation, lack of support, maternal youth, marital status,
poverty, parental
adverse childhood experiences, and parenting practices are all thought to contribute to increased risk. however, research indicates that socio-economic factors do not totally account for the racial disparities in infant mortality. It is only during deep recessions that infant mortality increases. According to Norbert Schady and Marc-François Smitz, recessions when
per capita GDP drops by 15% or more increase IMR. Social class dictates which medical services are available to an individual. Disparities due to
socioeconomic factors have been highlighted by advances in medical
technology. Developed countries, most notably the United States, have seen a divergence in IMR between those living in poverty who cannot afford medically advanced resources, and those who can. Levels of socioeconomic development and global integration are inversely related to a nation's infant mortality rate, meaning that as they increase, IMR decreases. A nation's internal impact is highly influenced by its position in the global economy, which has adverse effects on the survival of children in developing countries. which contributes to the global
division of labor, and distorts the
domestic economies of developing nations. The dependency of developing nations can reduce the rate of economic growth, increase income inequality inter- and intra-nationally, and adversely affect the wellbeing of a nation's population. Collective cooperation between countries plays a role in development policies in the poorer countries of the world.
War Infant mortality rates correlate with
war, political unrest, and
government corruption. Many other significant factors influence infant mortality rates in war-torn areas. Health care systems in developing countries in the midst of war often collapse, and obtaining basic medical supplies and care becomes increasingly difficult. During the
Yugoslav Wars in the 1990s, Bosnia experienced a 60% decrease in child immunizations. Preventable diseases can quickly become epidemics during war. Many developing countries rely on foreign aid for basic nutrition, and transport of aid becomes significantly more difficult in times of war. In most situations, the average weight of a population will drop substantially. Expectant mothers are affected even more by a lack of access to food and water. During the Yugoslav Wars in Bosnia, the number of premature babies born increased and the average birth weight decreased. Causes of infant mortality after abuse during pregnancy range from physical side effects of the initial trauma to psychological effects that lead to poor adjustment to society. Many people who became pregnant by rape in Bosnia were isolated from their hometowns, making life after childbirth exponentially more difficult.
Culture High rates of infant mortality occur in developing countries where financial and material resources are scarce, and where there is a high tolerance for infant deaths. There are a number of developing countries where certain cultural situations, such as favoring male babies over female babies, are the norm. Another cultural reason for infant mortality, such as what is happening in Ghana, is that "besides the obvious, like rutted roads, there are prejudices against wives or newborns leaving the house." This makes it even more difficult for pregnant women and newborns to get the needed treatment that is available to them. In the United States cultural influences and lifestyle habits can account for some infant deaths. Examples include
teenage pregnancy,
obesity,
diabetes, and
smoking. All are possible causes of premature births, which constitute the second-highest cause of infant mortality. According to the Journal of the American Medical Association, "the post neonatal mortality risk (28 to 364 days) was highest among continental Puerto Ricans" compared to non-Hispanic babies. Ethnic differences are accompanied by a higher prevalence of behavioral risk factors and sociodemographic challenges that each ethnic group faces. Genetic components result in newborn females being at a biological advantage when it comes to surviving their first birthday, versus newborn males, who have lower chances of surviving infancy. As infant mortality rates decreased globally, the gender ratios changed from males being at a biological disadvantage to females facing a societal disadvantage. Birth spacing is the time between births. Births spaced at least three years apart are associated with the lowest rate of mortality. The longer the interval between births, the lower the risk of having complications at birth, or of infant, childhood, or
maternal mortality. Conception less than six months after a birth, abortion, or miscarriage is associated with higher rates of preterm births and low birth weight, and also increases the chances of
chronic and general undernutrition. In 55 developing countries 57% of reported pregnancies had birth spaces of less than three years, and 26% of less than two years. While only 20% of new parents report wanting another birth within two years, only 40% are taking steps like
family planning to achieve this. Unplanned pregnancies and birth intervals of less than twenty-four months are known to correlate with low birth weights and delivery complications. Also, mothers who are already small in stature tend to deliver smaller than average babies, perpetuating a cycle of being
underweight. ==Prevention and outcomes==