Related Experiment Video
Updated: Feb 27, 2026
A Rat Model of Mild Intrauterine Hypoperfusion with Microcoil Stenosis
Published on: January 7, 2018
Birth Order and Injury-Related Infant Mortality in the U.S
Katherine A Ahrens1, Lauren M Rossen2, Marie E Thoma3
1Office of Population Affairs, Office of the Assistant Secretary for Health, U.S. DHHS, Rockville, Maryland.
Insights
Infants born second or later face a higher risk of death from injury in their first year of life. This study highlights the need to understand why later-born infants experience increased injury mortality risks.
Area of Science:
- Public Health
- Epidemiology
- Pediatric Mortality
Background:
- Infant mortality due to injury is a significant public health concern in the U.S.
- Birth order is a demographic factor that may influence infant health outcomes.
- Previous research has not fully elucidated the association between birth order and injury-related infant mortality.
Purpose of the Study:
- To assess the association between birth order and the risk of infant mortality due to injury.
- To compare the risk of injury-related death in second, third, fourth, and fifth or later-born singleton infants versus first-born infants.
- To provide data for targeted injury prevention strategies.
Main Methods:
- Utilized national birth cohort-linked birth-infant death data from 2000-2010 (births) and 2000-2011 (deaths).
- Compared risks of infant mortality due to injury across different birth orders for singleton infants.
- Employed log-binomial regression models, adjusting for maternal age, marital status, race/ethnicity, and education.
Main Results:
- Second or later-born singleton infants demonstrated a significantly increased risk of mortality due to injury compared to first-born infants.
- Adjusted risk ratios for injury-related infant mortality increased with birth order: second (1.84), third (2.42), fourth (2.96), and fifth or later (4.26).
- Approximately 1,442 injury-related infant deaths occurred annually in the U.S. between 2000 and 2011.
Conclusions:
- Singleton infants born second or later are at a demonstrably higher risk of death from injury within the first year of life.
- The findings underscore the necessity of further research into the mechanisms driving this elevated risk.
- Public health interventions may need to consider birth order as a factor in infant injury prevention efforts.
Introduction:
The purpose of this study was to evaluate the risk of death during the first year of life due to injury, such as unintentional injury and homicide, by birth order in the U.S.
Methods:
Using national birth cohort-linked birth-infant death data (births, 2000-2010; deaths, 2000-2011), risks of infant mortality due to injury in second-, third-, fourth-, and fifth or later-born singleton infants were compared with first-born singleton infants. Risk ratios were estimated using log-binomial models adjusted for maternal age, marital status, race/ethnicity, and education. The statistical analyses were conducted in 2016.
Results:
Approximately 40%, 32%, 16%, 7%, and 4% of singleton live births were first, second, third, fourth, and fifth or later born, respectively. From 2000 to 2011, a total of 15,866 infants died as a result of injury (approximately 1,442 deaths per year). Compared with first-born infants (2.9 deaths per 10,000 live births), second or later-born infants were at increased risk of infant mortality due to injury (second, 3.6 deaths; third, 4.2 deaths; fourth, 4.8 deaths; fifth or later, 6.4 deaths). The corresponding adjusted risk ratios were as follows: second, 1.84 (95% CI=1.76, 1.91); third, 2.42 (95% CI=2.30, 2.54); fourth, 2.96 (95% CI=2.77, 3.16); and fifth or later, 4.26 (95% CI=3.96, 4.57).
Conclusions:
Singleton infants born second or later were at increased risk of mortality due to injury during their first year of life in the U.S. This study's findings highlight the importance of investigating underlying mechanisms behind this increased risk.
Related Concept Videos
01:20Attachment
01:27Fractures: Bone Repair
Minor fractures with no bone displacement are treated by immobilizing the fractured bone using a cast or splint. However, in the case of fractures with displaced bones, the broken bones are repositioned before immobilization to ensure successful healing without deformation and loss of function. The realignment of fractured bone ends is performed through a process called reduction. If the...
01:29Relationship with Other Adult Family Members and Siblings
01:35Pedigree Analysis
01:28Relationship with Parents: Attachment