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Infant mortality

Infant mortality is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Infant mortality rather than just read about it. In short: Infant mortality is the death of an infant before its first birthday. The occurrence of infant mortality in a population can be described by the infant mortality rate (IMR), which is the number of deaths of infants under one year of age per 1,000 live births.

Infant mortality — main illustration
Infant mortality — illustration

Key takeaways

  • Infant mortality belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Infant mortality to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Infant mortality from memory before moving on to harder problems.

Reference excerpt

Infant mortality is the death of an infant before its first birthday. The occurrence of infant mortality in a population can be described by the infant mortality rate (IMR), which is the number of deaths of infants under one year of age per 1,000 live births. Similarly, the child mortality rate, also known as the under-five mortality rate, compares the death rate of children up to the age of five. Leading causes of infant mortality include birth asphyxia, pneumonia, neonatal infection, diarrhea, malaria, measles, malnutrition, term birth complications such as abnormal presentation of the fetus, umbilical cord prolapse, or prolonged labor. One of the most common preventable causes of infant mortality is smoking during pregnancy. Lack of prenatal care, alcohol consumption during pregnancy, and drug use also cause complications that may result in infant mortality. Many situational factors contribute to the infant mortality rate, such as the pregnant woman's level of education, environmental conditions, political infrastructure, and level of medical support. Improving sanitation, access to clean drinking water, immunization against infectious diseases, and other public health measures can help reduce rates of infant mortality. In 1990, 8.8 million infants younger than one-year-old died globally out of 12.6 million child deaths under the age of five. More than 60% of the deaths of children under-five are seen as avoidable with low-cost measures such as continuous breastfeeding, vaccinations, and improved nutrition. The global under-five mortality rate in 1950 was 22.5%, which dropped to 4.5% in 2015. Over the same period, the infant mortality rate declined from 65 deaths per 1,000 live births to 29 deaths per 1,000. Globally, 5.4 million children died before their fifth birthday in 2017; by 2021 that number had dropped to 5 million children. The child mortality rate (not the infant mortality rate) was an indicator used to monitor progress towards the Fourth Goal of the Millennium Development Goals of the United Nations for the year 2015. A reduction in child mortality was established as a target in the Sustainable Development Goals—Goal Number 3: Ensure healthy lives and promote well-being for all at all ages. As of January 2022, an analysis of 200 countries found 133 already meeting the SDG target, with 13 others trending towards meeting the target by 2030. Throughout the world, the infant mortality rate (IMR) fluctuates drastically, and according to Biotechnology and Health Sciences, education and life expectancy in a country are the leading indicators of IMR. This study was conducted across 135 countries over the course of 11 years, with the continent of Africa having the highest infant mortality rate of any region studied, with 68 deaths per 1,000 live births.

Classification Infant mortality rate (IMR) is the number of deaths per 1,000 live births of children under one year of age. The rate for a given region is the number of children dying under one year of age, divided by the number of live births during the year, multiplied by 1,000. Forms of infant mortality:

Perinatal mortality is late fetal death (22 weeks gestation to birth) or death of a newborn up to one week postpartum. Neonatal mortality is death occurring within 28 days postpartum. Neonatal death is often attributed to inadequate access to basic medical care, during pregnancy and after delivery. This accounts for 40–60% of infant mortality in developing countries. Postneonatal mortality is the death of children aged 29 days to one year. The major contributors to postneonatal death are malnutrition, infectious disease, pregnancy complications, sudden infant death syndrome, and problems in the home environment.

Causes 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. While 99% of infant deaths occur in developing countries, the greatest percentage reduction in infant mortality occurs in countries that already have low rates of infant mortality. 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%.

Premature birth

… excerpt ends here. Continue reading the full article.

Illustrations

Infant mortality: World map of infant mortality rates in 2023
World map of infant mortality rates in 2023
Infant mortality: Percentage of population suffering from hunger, World Food Programme, 2020 .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  < 2.5%   2.5–5.0%   5.0–14.9%   15.0–24.9%   25.0–34.9%   > 35.0%   No data
Percentage of population suffering from hunger, World Food Programme, 2020 .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  < 2.5%   2.5–5.0%   5.0–14.9%   15.0–24.9%   25.0–34.9%   > 35.0%   No data
Infant mortality: Infant mortality rates are higher in countries with higher economic inequality.
Infant mortality rates are higher in countries with higher economic inequality.
Infant mortality: Countries or territories by GDP (PPP) per capita in 2025   >$70,000   $60,000 – $70,000   $50,000 – $60,000   $40,000 – $50,000   $30,000 – $40,000   $20,000 – $30,000   $10,000 – $20,000   $5,000 – $10,000   $2,500 – $5,000   $1,000 – $2,500   <$1,000   No data
Countries or territories by GDP (PPP) per capita in 2025   >$70,000   $60,000 – $70,000   $50,000 – $60,000   $40,000 – $50,000   $30,000 – $40,000   $20,000 – $30,000   $10,000 – $20,000   $5,000 – $10,000   $2,500 – $5,000   $1,000 – $2,500   <$1,000   No data
Infant mortality: Map of countries by total fertility rate (2022–2023), referring to the average number of children that are born to a woman over her lifetime, according to the Population Reference Bureau.[91]
Map of countries by total fertility rate (2022–2023), referring to the average number of children that are born to a woman over her lifetime, according to the Population Reference Bureau.[91]

Worked examples

Example 1 — a first encounter with Infant mortality

Start with the simplest possible case. Write down what Infant mortality claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Infant mortality before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Infant mortality ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Infant mortality

In research
Infant mortality appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Infant mortality in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Infant mortality is common in secondary-school and first-year university syllabi. It links to neighbouring topics Infant mortality, Population, Public health, so understanding it makes those chapters shorter.
In everyday life
Look for Infant mortality outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Infant mortality in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Infant mortality means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Infant mortality out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Infant mortality in simple terms?

Infant mortality is the death of an infant before its first birthday. The occurrence of infant mortality in a population can be described by the infant mortality rate (IMR), which is the number of deaths of infants under one year of age per 1,000 live births.

Why does Infant mortality matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Infant mortality?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Infant mortality.

Tags

  • Infant mortality
  • Population
  • Public health

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