The sex ratio at birth (SRB) refers to the number of male births for every 100 female births. Typically, biological factors lead to a slightly higher number of males being born than females. However, the overall sex ratio in a population, which encompasses all age groups, tends to even out over time as females generally have a higher life expectancy than males, meaning women tend to outnumber men in older age groups.

The sex ratio can be represented by the following formula:

Sex Ratio=(Number of females/ Number of males)×1000 

This ratio gives a snapshot of the balance between the two sexes in a population, allowing for comparisons over time and across regions. A sex ratio of 1000 indicates an equal number of males and females, while a ratio higher than 1000 suggests more females and a ratio lower than 1000 indicates more males.