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Health Indicator Report of Sex Ratio at Birth

The expected sex ratio at birth (male to female) is 1.05, or 5% more males born than females. Population growth is, in part, related to the number of live male children. Numerous studies have reported changes in the ratio of males to females at birth; many of the studies have found a reduction in male relative to female births in different countries throughout the world.

Sex Ratio at Birth by Year, 1989-2013

Data Source

Office of Vital Records and Statistics, Utah Department of Health


The sex ratio at birth is the comparison of male births to female births. The expected sex ratio at birth (male to female) is 1.05, or 5% more males born than females.


Number of live male births in a specific period of time; number of live female births in a specific period of time.


Total number of live births in a specific period of time.

Other Objectives

Some factors can affect the sex of a newborn. Decreases in male births have been shown to be inversely related to parental smoking, gestation length, parental age, and birth order. Reproductive practices and social constructs regarding sex preferences- males over females, for example, can affect the observed sex ratio. Although the mechanism which determines the sex of the infant is not completely understood, some environmental studies have suggested that environmental hazards can affect how many males are born. Biological parent(s) and/or the fetus can come in contact with and become exposed to different hazards referred to as endocrine disruptors. Fewer males are conceived when exposure to endocrine disruptors results in a decrease in testosterone.

What Is Being Done?

The Office of Vital Records and Statistics at the Utah Department of Health records all birth records along with their associated sex.
Page Content Updated On 07/21/2015, Published on 07/27/2015
The information provided above is from the Department of Health's Center for Health Data IBIS-PH web site ( The information published on this website may be reproduced without permission. Please use the following citation: " Retrieved Sun, 04 October 2015 19:23:53 from Department of Health, Center for Health Data, Indicator-Based Information System for Public Health Web site: ".

Content updated: Tue, 28 Jul 2015 19:46:19 MDT