Age at First Sexual Intercourse

 

Percentage who had first sexual intercourse by specific exact ages

 

Definition

 

1)     Percentage of women and men who first had sexual intercourse before attaining the specific exact ages.

2)     Percentage of women and men who never had sexual intercourse.

 

Coverage:

Population base: Women and men age 15-49 (IR file, MR file)

Time period: Lifetime of the respondent

 

Numerators:

1)     Number of women (or men) who had their first sexual intercourse before they attainedthe specific age (women: v531 < specific age; men: mv531 < specific age)

2)        Number of women (or men) who never had sexual intercourse (women: v531 = 0; men: mv531 = 0)

 

Denominator: Number of women (or men) age 15-49

 

Variables: IR file, MR file.

v531

Age at first sexual intercourse (imputed) (women)

v005

Woman’s individual sample weight

awfactt

All women factor (only needed with ever-married samples)

mv531

Age at first sexual intercourse (imputed) (men)

mv005

Man’s individual sample weight

amfactt

All man factor (only needed with ever-married samples)

 

Calculation

 

Age at first sexual intercourse: Reported by woman or man as age in completed years or when they first had sex. This age is imputed for those who reported the age at first sex was the same as their age at first union.

 

Numerators: Number of women (or men) who first had sexual intercourse below the specific exact ages (15, 18, 20, 22, 25) includes women (or men) who first had sexual intercourse before earlier specific ages, e.g. the number of women (or men) who first had sexual intercourse before age 18 includes those who had sexual intercourse before age 15. Women (or men) who have never had sexual intercourse are included in a separate category.

 

Denominator: Number of women (or men) of all marital statuses. Numerators for each specified age are divided by the overall denominator and multiplied by 100. In ever-married samples, denominators are adjusted by the all women (or all men) factors. This denominator may need to be restricted (see Notes and Considerations below).

 

Handling of Missing Values

 

Women or men with unknown and missing ages at first sexual intercourse are excluded from the numerators, but included in the denominator. Women or men whose imputed age at sex is inconsistent (women: v531=97; men: v531=97) are excluded from the numerators, but included in the denominator.

 

Notes and Considerations

 

When presenting this indicator by age groups, percentages for the specified age at first sexual intercourse are not calculated for those groups of age where the youngest member of the age group has not yet reached that specified age. For example, percentages for women 20–24 at the time of the survey will not be calculated for the specified age 22, or 25 because the cohort is truncated and some women or men who have never had intercourse are still below those ages and could still have their first intercourse within the age group categories.

 

In many ever-married samples, age at first sexual intercourse was not asked. In the other ever-married surveys, never-married women or men are assumed not to have had sexual intercourse, and their all women or men factor is tallied in the category for never had sexual intercourse.

 

Changes over Time

 

Some rounds of DHS included a category 96 for age at first union (women: v525=96; men: mv525=96) for when the woman or man began living with their spouse or consensual partner. In the DHS standard recode variable v531 (or mv531 for men) (age at first sex (imputed)) this response has been converted to the age at first union in completed years.

 

Resources

 

DHS-7 Tabulation plan: Table 4.5

 

API Indicator IDs:

Women:

SX_SBAG_W_B15, SX_SBAG_W_B18, SX_SBAG_W_B20, SX_SBAG_W_B22, SX_SBAG_W_B25, SX_SBAG_W_NSX

Men:

SX_SBAG_M_B15, SX_SBAG_M_B18, SX_SBAG_M_B20, SX_SBAG_M_B22, SX_SBAG_M_B25, SX_SBAG_M_NSX

(API link, STATcompiler link)


 

Median age at first sexual intercourse

 

Definition

 

Median age in years at first sexual intercourse.

 

Coverage:

Population base: Women and men of all marital statuses. (IR file, MR file)

Time period: Lifetime of the respondent

 

Median: Median for completed time periods

 

Variables: IR file, MR file.

v531

Age at first sexual intercourse (imputed) (women)

v005

Woman’s individual sample weight

awfactt

All women factor (only needed with ever-married samples)

mv531

Age at first sexual intercourse (imputed) (men)

mv005

Man’s individual sample weight

amfactt

All man factor (only needed with ever-married samples)

 

Calculation

 

Medians are calculated from cumulated single-year percent distributions (see Numerator and Denominator of Age at First Sexual Intercourse. Median is linearly interpolated between the single-year percent distributions that occur at the ages before and after 50 percent of the women (or men) had sexual intercourse for the first time. (See Median Calculations in Chapter 1).

 

Numerators: Number of women (or men) within single year of age categories of age at first sexual intercourse (women: v531; men: mv531). Women (or men) who have never had sexual intercourse are included in a separate category at the tail of the distribution. In ever-married samples, the all women (or all men) factor is tallied in the category of women (or men) who have never been married or lived in a consensual union.

 

Denominator: Number of women (or men) of all marital statuses. Numeratorsare divided by the overall denominator and multiplied by 100 to obtain percentages. In ever-married samples the denominator is adjustedby the all women (or all men) factors.

 

Handling of Missing Values

 

Women and men with unknown and missing ages at first sexual intercourse are excluded from both the denominator and the numerators. Women and men with inconsistent ages at first sexual intercourse (women: v531=97; men: mv531=97) or who did not know their age at first sex (women: v531=98; men: mv531=98) are excluded from the numerator but included in the denominator.

 

Notes and Considerations

 

The reported age at first sexual intercourse is in completed years (e.g., women reporting 19 years of age at first sexual intercourse includes all women who had their first sexual intercourse under 20 years of age).

 

Since the median is based on all women or men, including those who never had sexual intercourse, there may not be a median for younger cohorts of women or men (since fewer than 50 percent of the cohort may have had sexual intercourse). Medians are omitted for women or men whose current age interval includes or precedes the median age at first sex.

 

In most of the ever-married DHS surveys, age at first sexual intercourse was not asked. In the ever- married surveys that included questions on age at first sexual intercourse, never-married women or men are assumed not to have had sexual intercourse.

 

Changes over Time

 

Some rounds of DHS included a category 96 for age at first union (women: v525=96; men: mv525=96) for when the woman or man began living with her/his first spouse or consensual partner. In the DHS standard recode variables v531/mv531 (age at first sex (imputed)) this response has been converted to the age at first union in completed years.

 

Example

 

For example, the figure below shows the cumulative (weighted) percentage of women age 20-49 who reported having first had sex at specific ages. We look for two successive cumulative percentages that bracket 50%. We find that 41% of women age 20-49 had experienced their sexual debut at 15 (by 16th birthday) and 56% at age 16 (by 17th birthday). Because we know that cumulatively, 50% of women age 20-49 had sex between the 16th birthday and the 17th birthday, we know the median age is 16. To be more precise we interpolate between 16.0 and 17.0.  The interpolation between these two points reveals a median of 16.6 or the age at which 50% of women age 20-49 experienced first sex is 16.6.

 

Median = 16.6

 

Mathematically, this is equivalent to calculating an interpolated median between the completed ages 17 and 18, and adding one to the result.

 

References

 

MacQuarrie, K. L.D., L. Mallick, and C. Allen. 2017. Sexual and Reproductive Health in Early and Later Adolescence: DHS Data on Youth Age 10-19. DHS Comparative Reports No. 45. Rockville, Maryland, USA: ICF. https://dhsprogram.com/publications/publication-CR45-Comparative-Reports.cfm

 

Resources

 

DHS-7 Tabulation plan: Tables 4.5, 4.6

 

API Indicator IDs: SX_AAFS_W_M2A, SX_AAFS_W_M2B, SX_AAFS_M_M2A, SX_AAFS_M_M2B

(API link, STATcompiler link)