Age-Specific Fertility Fate (ASFR): Based on Age-Period Rates
Coverage:
Population base: Women age 15-49 years in seven five-year age groups (15-19, 20-24, 25-29, 30-34, 35-39, 40-44, 45-49 years) (IR file)
Time period: Three years preceding the survey
Numerator: Number of births that occurred in a period (typically the 1-36 months before the survey) to women in the age group at the time of the birth (v008 - b3 in 1:36) (BR file)
Denominator: Number of women-years of exposure in the same period (1-36 months before the survey) of women in the age group (IR file)
Variables: BR file, IR file.
|
b3 |
CMC date of birth of child |
|
v011 |
CMC date of birth of respondent |
|
v008 |
CMC date of interview |
|
v005 |
Woman’s individual sample weight |
|
awfactt |
All women factor (only needed with ever-married samples) |
The age-specific fertility rate is calculated as the quotient of the numerator divided by the denominator for each age group, multiplied by 1000. The result is an average rate over the 36-month period, expressed as an annual rate per 1000 women.
Numerator: Births are tabulated according to period of birth and the age of mother at the time of the birth:
Period of birth: The period of birth is calculated as the difference in months between the date of
interview and the date of birth, both in century-month code format (CMC). Births are included in the tabulation if they occur 1-36 months before the survey (v008 - b3 in 1:36).
Age of mother at the time of the birth: The difference in months between the date of birth of the child and the date of birth of the mother both in CMC. The difference is then divided by 60 and truncated to whole numbers to form the age groups (agegroup = int( (b3 - v011) /60) ). Note that age group 15-19 is classified as age group 3 here, not age group 1. Births are tabulated by age group.
Denominator: Women-years of exposure are calculated as the sum of the number of months exposed in the five-year age group during the time period divided by 12. A woman can contribute exposure to several age groups in the period, depending on the length of the period. For periods exceeding five years a woman can contribute to more than two age groups. For a period of three years or five years a woman will contribute to no more than two five-year age groups during the 36- or 59-month period. The description below assumes a period of 1-36 months preceding the survey, and that a woman contributes to at most two age groups, described here as the higher age group and the lower age group:
Higher age group: A woman’s age at the end of the period determines the higher age group. The higher age group is calculated by subtracting the women’s date of birth from the date of interview minus one (in CMC), dividing the difference by 60 and truncating to a whole number (agegroup = int( (v008-1-v011)/60 ). The -1 is to ignore the month of interview and use just the 36 months prior to but not including the month of interview.
The number of months spent in the higher age group is the difference in months between her age at the end of the period of exposure (date of interview less one month) and the lower age limit of the age group plus one month (exposure = v008 - 1 - v011 - agegroup*60 + 1). As the -1 and the +1 cancel out this can be simplified to (exposure = v008 - v011 - agegroup*60). If the number of months in the age group exceeds 36 then the exposure is truncated to 36 for the period (exposure = 36 if exposure > 36). If the number of months in the age group is less than the duration of the time period (36 months), then the woman contributes exposure to both the higher age group and the next lower age group (agegroup-1).
Lower age group: The contribution to the lower age group is 36 less the number of months of exposure in the higher age group. If the number of months in the higher age group is greater than the duration of the time period (i.e., >36 months), then the exposure in the higher group is the duration of the period (36 months) and the exposure in the lower age group is zero.
Tabulation: Each woman is tallied twice, once according to her higher age group accumulating the exposure she contributes to that group and once in the lower age group accumulating lower age group exposure. For ever-married samples, the exposure is adjusted to represent all women by multiplying the exposure by the woman’s “all women factor” (awfactt), which is derived from the proportion of women ever-married from the persons data file (PR file). See the section on All Women Factors for details on their calculation. The total exposure in each age group is then the sum of the exposure in each age group from the first and second tallying.
Example 1: A woman interviewed in December 2017, born in May 1986. Her CMC date of interview is 12*(2017 - 1900) + 12 = 1416. The CMC of the date of the end of the period of exposure is 1416 - 1 = 1415. Her CMC date of birth is 12*(1986 - 1900) + 5 = 1037. Her age in months at the end of the period is 1415 - 1037 = 378. The age group at the end of the period is 378/60 = 6.3, truncated to 6. This represents age group 30-34 years (30 = 6*5 years interval). The number of months in this age group is 378 - 6*60 + 1 = 19 months. Since this is less than the total number of months during the period (36 months), she contributed 19 months to age group 30-34 during the period and 36 - 19 = 17 months to the age group 25-29 during the period.
Example 2: A woman interviewed in December 2017, born in March 1983. Her CMC date of interview is 12*(2017 - 1900) + 12 = 1416. The date of the end of the period of exposure is 1416 - 1 = 1415. Her CMC date of birth is 12*(1983 - 1900) + 3 = 999. Her age in months at the end of the period is 1415 - 999 = 416. The age group at the end of the period is 416/60 = 6.93, truncated to 6. This represents age group 30-34 years (30 = 6*5 years interval). The number of months in this age group is 416 - 6*60 + 1 = 57 months. Since the number of months in this age group is greater than 36 months, she contributed 36 months of exposure to age group 30-34 during the period and no exposure to the next lower age group during the period.
The total number of children to which a woman has given birth is recorded obligatorily by the interviewer; no unknown numbers of children are allowed. There are three values involved in the calculation of ASFR, interview date, birth date of woman and birth dates of children. The interview date is always known from fieldwork dates. If missing or unknown, the birth dates of interviewed women and her children are imputed before formation of the standard recode file. See Date Variables in Chapter 1.
The Age-Specific Fertility Rate (ASFR) is also known as the Age-Period Fertility Rate. The ASFR is typically calculated for the three years that precede the date of the survey and is presented as an annual rate.
The ASFR for women in the age group 15-19 is also known as the Adolescent Birth Rate (ABR).
Births to women at ages less than 15 years or more than 49 years at the time of the birth are not included in the calculation of these ASFRs, however births to girls age 10-14 at the time of birth are included in the calculation of the ASFR 10-14.
Births in the month of interview are excluded. This exclusion is because this month does not represent a full month but is censored by the date of interview.
A three-year (36 month) time period is taken for calculating current ASFR. This period is a compromise between the need for recency and reduction of sampling variation. This time period was selected during the World Fertility Survey, when sample sizes were on average about 5,000 women. For comparability over time and across surveys, this period has been maintained by The DHS Program.
No adjustment is made for truncation by age. Women who are at most 49 years at the time of interview were 48 years the year before and 47 years two years before. The reason no adjustment is made is that the tiny probability of women age 48 and 49 years of age giving birth in the three years preceding the survey outweighs the complication of adjusting by single years of age.
In line with general DHS policy, no adjustment is made for possible omission or date misreporting of the dates of birth of children or misreporting of the date of birth of the woman.
For ever-married samples, it is assumed that never-married women have not had any births. Only the denominator of the rates is adjusted to estimate the number of all women exposed in the age group.
Croft, T. 1991. “Date Editing and Imputation”. In Demographic and Health Surveys World Conference Proceedings, II: 1337-1356, Columbia, Maryland: IRD/ORC Macro. https://dhsprogram.com/publications/publication-DHSG3-DHS-Questionnaires-and-Manuals.cfm
Moultrie, T.A. 2013. Direct estimation of fertility from survey data containing birth histories. In Moultrie, T.A., R. E. Dorrington, A. G. Hill, K. Hill, I. M. Timæus and B. Zaba (eds). Tools for Demographic Estimation. Paris: International Union for the Scientific Study of Population. http://demographicestimation.iussp.org/content/direct-estimation-fertility-survey-data-containing-birth-histories
Pullum, T, S. Assaf, and S. Staveteig. 2017. Comparisons of DHS Estimates of Fertility and Mortality with Other Estimates. DHS Methodological Reports No. 21. Rockville, Maryland, USA: ICF. https://www.dhsprogram.com/publications/publication-MR21-Methodological-Reports.cfm
Pullum, T. W. 2004. “Natality: Measures based on censuses and surveys.” Chapter 16 of The Methods and Materials of Demography, 2nd edition, edited by D.A. Swanson and J. Siegel, 407-428, San Diego, California: Academic Press. https://demographybook.weebly.com/uploads/2/7/2/5/27251849/david_a._swanson_jacob_s._siegel_the_methods_and_materials_of_demography_second_edition__2004.pdf
Pullum, T. W. and S. Becker. 2014. Evidence of omission and displacement in DHS birth histories. DHS Methodological Reports No. 11. Rockville, Maryland, USA: ICF International. https://www.dhsprogram.com/publications/publication-MR11-Methodological-Reports.cfm
Schoumaker, B. 2011. "Omissions of births in DHS birth histories in sub-Saharan Africa: Measurement and determinants". Paper presented at Population Association of America, Washington D.C., March 31 - April 2, 2011. http://paa2013.princeton.edu/papers/132148
Schoumaker, B. 2013. “A Stata module for computing fertility rates and TFRs from birth histories: tfr2.” Demographic Research 28:1093–1144. http://doi.org/10.4054/DemRes.2013.28.38
Schoumaker, B. 2014. Quality and Consistency of DHS Fertility Estimates, 1990 to 2012. DHS Methodological Reports No. 12. Rockville, Maryland, USA: ICF International. https://www.dhsprogram.com/publications/publication-MR12-Methodological-Reports.cfm
R package DHS.rates: Calculate Key DHS Indicators: https://CRAN.R-project.org/package=DHS.rates
DHS-8 Tabulation plan: Table 5.1
API Indicator IDs:
FE_FRTR_W_A15, FE_FRTR_W_A20, FE_FRTR_W_A25, FE_FRTR_W_A30,
FE_FRTR_W_A35, FE_FRTR_W_A40, FE_FRTR_W_A45
SDG Indicator 3.7.2: Adolescent birth rate (15-19)
WHO 100 Core Health Indicators: Adolescent birth rate (15-19)
MICS6 Indicator TM.1: Adolescent birth rate (ASFR 15-19)
Age-Specific Fertility Rate (ASFR) for age group 10-14: Based on Age-Period Rates
Coverage:
Population base: All girls age 10-14 years during the time period (IR file)
Time period: Three years preceding the survey
Numerator: Number of births that occurred in a period (typically the 1-36 months or 1-60 months before the survey) to girls in the age group 10-14 at the time of the birth (v008 - b3 in 1:36 [or 60]) (BR file)
Denominator: Number of years of exposure in the same period of girls in the age group 10-14 (IR file)
Variables: BR file, IR file.
|
b3 |
CMC date of birth of child |
|
v011 |
CMC date of birth of respondent |
|
v008 |
CMC date of interview |
|
v005 |
Woman’s individual sample weight |
|
awfactt |
All women factor (only needed with ever-married samples) |
The ASFR 10-14 is calculated as the quotient of the numerator divided by the denominator for each age group, multiplied by 1000. The result is an average rate over the 36- or 59-month period, expressed as an annual rate per 1000 women. The age-specific fertility rate for age group 10-14 is calculated in a similar manner to the ASFRs for age groups between 15 and 49, but with adjustments to both numerator and denominator to avoid biases as girls age 10-14 are not typically interviewed in DHS surveys, and the ASFR 10-14 is based on retrospective data for women age 15-19.
Numerator: Births are tabulated according to period of birth and the age of mother at the time of the birth, and are adjusted for truncation of reports:
Period of birth: The period of birth is calculated as the difference in months between the date of interview and the date of birth, both in century-month code format (CMC). Births are included in the tabulation if they occur 1-36 months before the survey (v008 - b3 in 1:36 [or 60]).
Age of mother at the time of the birth: The difference in months between the date of birth of the child and the date of birth of the mother both in CMC. The difference is then divided by 12 and truncated to whole numbers to form single year age groups (singleage = int( (b3 - v011) /12 ). Births are tabulated by single year age group for ages 10-14. Note that the use of single year age groups is different than the five-year age groups used for ASFRs for ages 15 to 49.
Adjustment of number of births due to truncation of reports: Figure 5.1 below shows the reports available for the calculation of ASFR 10-14 (in blue) and the data not available due to truncation (in red) for both a three-year period and a five-year period immediately preceding the survey. For a three-year (36-month) period, for age 14 data are reported for 5/6 of the births and exposure, for age 13 for 3/6, and for age 12 for 1/6. For ages 11 and 10 no data are reported. The births for ages 12-14 are thus adjusted by the inverse of these proportions – 6/5 for age 14, 6/3 for age 13, and 6/1 for age 12. For ages 11 and 10, the assumption is that there are no births in these age groups (in total over more than 200 DHS surveys there were 9 births reported at age 11 and 1 birth at age 10 in the five years preceding the survey). For a five-year (60-month) period similar adjustments of 10/9, 10/7, 10/5, 10/3, 10/1 are made for ages 14, 13, 12, 11, and 10 respectively. After adjusting the births, the total births in each single age is summed to produce an aggregate for the age group 10-14.
Figure 5.1 |
Denominator: Person-years of exposure are calculated as the sum of the number of months exposed in each single-year age group for ages 10-14 during the time period, adjusted for truncation of reports (see below), divided by 12. A girl can contribute exposure to several single year ages in the period, depending on the length of the period, and may contribute to x+1 single year ages for a period covering x years.
Oldest age: A girl’s age at the end of the period determines the oldest age. The oldest age is calculated by subtracting the girl’s date of birth from the date of interview minus one (in CMC), dividing the difference by 12 and truncating to a whole number (singleage = int( (v008-1-v011)/12 ). The -1 is to ignore the month of interview and use just the 36 (or 60) months prior to but not including the month of interview.
The number of months spent in the oldest age is the difference in months between her age in months at the end of the period of exposure (date of interview less one month) and the lower age limit in months of the age group plus one month (exposure = v008 - 1 - v011 - singleage*12 + 1). As the -1 and the +1 cancel out this can be simplified to (exposure = v008 - v011 - singleage*12). The remaining exposure (to be covered by other ages) is 36 or 60 minus the exposure.
Other ages: Starting one year before the oldest age, the contribution of exposure to other ages is the minimum of either 12 months or the remaining exposure in months. After tallying the exposure for a single year age, the remaining exposure is reduced by the amount contributed, the single year age is reduced by one year and the tallying repeated for the next lower age until the remaining exposure is 0 or the age is outside of 10-14.
Tabulation: Each girl is tallied once per single year age for each age she was exposed for in the period, accumulating the exposure she contributes to that age. For ever-married samples, the exposure is adjusted to represent all girls by multiplying the exposure by the “all women factor” (awfactt), which is derived from the proportion of women ever-married from the persons data file (PR file). See the section on All Women Factors for details on their calculation in Chapter 1. The total exposure in the age group 10-14 is then the sum of the exposure in each single age adjusted for truncation of reports (see below).
Adjustment of years of exposure due to truncation of reports: As for the births, similar adjustments are made for the exposure. For a 36-month period the exposure for ages 12-14 are thus adjusted by the inverse of these proportions – 6/5 for age 14, 6/3 for age 13, and 6/1 for age 12. After adjusting the exposure, the total exposure in each single age is summed to produce an aggregate for the age group 12-14. As no exposure is collected for ages 11 and 10, the assumption is that the exposure per single year age for ages 10 and 11 is the same as the average for ages 12-14, and so the exposure is multiplied by 5/3 to produce an estimate of exposure for ages 10-14. For a 60-month period, similar adjustments of 10/9, 10/7, 10/5, 10/3, 10/1 are made to the single year exposure for ages 14, 13, 12, 11, and 10 respectively before summing the total exposure for ages 10-14.
Example 1: A woman interviewed in December 2017, born in September 2002. Her CMC date of interview is 12*(2017 - 1900) + 12 = 1416. The date of the end of the period of exposure is 1416 - 1 = 1415. Her CMC date of birth is 12*(2002 - 1900) + 9 = 1233. Her age in months at the end of the period is 1415 - 1233 = 182. The single age group at the end of the period is 182/12 = 15.17, truncated to 15. The number of months in this age group is 182 - 15*12 + 1 = 3 months. For the oldest age group (15) she would contribute 3 months, however, age 15 is outside the age group range of 10-14, so no tallying is done for this age group. The remaining exposure in the 36-month period would be 36 – 3 = 33 months. For the next age younger group (14) she contributes the minimum of the remaining exposure (33 months) or 12 months, so thus contributes 12 months and the remaining exposure becomes 21 months. For age 13 she again contributes 12 months, and the remaining exposure becomes 9 months. For age 12 she contributes just the remaining exposure (9 months) to this age in the period.
Summary of exposure for example 1:
|
Age |
Exposure |
Remaining exposure |
Tallying |
|
15 |
3 |
33 |
No tallying as too old |
|
14 |
12 |
21 |
12 months at age 14 |
|
13 |
12 |
9 |
12 months at age 13 |
|
12 |
9 |
0 |
9 months at age 12 |
Example of adjustments for births and exposure for three-year period:
|
Age |
Births |
Exposure |
Adjustment |
Births adjusted |
Exposure adjusted |
|
12 |
1 |
450 |
6/1 |
6 |
2700 |
|
13 |
8 |
1500 |
6/3 |
16 |
3000 |
|
14 |
20 |
2500 |
6/5 |
24 |
3000 |
|
Sum for 12-14 |
|
|
|
46 |
8700 |
|
Sum for 10-14 |
|
|
5/3 for exposure only |
46 |
14500 |
|
ASFR 10-14 |
|
|
Births/Exposure |
|
.003 |
The total number of children to whom a woman has given birth is recorded obligatorily by the interviewer; no unknown numbers of children are allowed. There are three values involved in the calculation of ASFR, interview date, birth date of woman and birth dates of children. The interview date is always known from fieldwork dates. If missing or unknown, the birth dates of interviewed women and her children are imputed before formation of the standard recode file. See Date Variables in Chapter 1.
The ASFR 10-14 is typically calculated for the three years that precede the date of the survey and is presented as an annual rate.
Births to women while age 15 or higher are not included in the calculation of the ASFR 10-14, however, births to girls age 10-14 at the time of birth are included in the calculation of the ASFR 10-14.
Births in the month of interview are excluded. This exclusion is because this month does not represent a full month but is censored by the date of interview.
In line with general DHS policy, no adjustment is made for possible omission or date misreporting of the dates of birth of children or misreporting of the date of birth of the woman.
For ever-married samples, it is assumed that never-married women have not had any births. Only the denominator of the rates is adjusted to estimate the number of all women exposed in the age group.
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
Pullum, T., and T. Croft. 2018. Methods to Estimate Under-15 Fertility
Using Demographic and Health Surveys Data. DHS Methodological Report No. 23. Rockville, Maryland, USA: ICF. https://www.dhsprogram.com/publications/publication-MR23-Methodological-Reports.cfm
Way, A. 2014. Youth data collection in DHS surveys: An overview. DHS Occasional Papers No. 9. Rockville, Maryland, USA: ICF International. https://www.dhsprogram.com/publications/publication-OP9-Occasional-Papers.cfm
DHS-8 Tabulation plan: Table 5.1
API Indicator ID:
FE_FRTR_W_A10
SDG Indicator 3.7.2: Adolescent birth rate (10-14)
WHO 100 Core Health Indicators: Adolescent birth rate (10-14)
Age-Specific Fertility Rate (ASFR) for five-year periods preceding the survey: Based on Age-Period Rates
Coverage:
Population base: Women age 15-49 (IR file)
Time period: Five-year (or four-year) periods preceding the survey
The calculation of ASFRs for trends is the same as the calculation of current ASFRs, except that they are calculated for either five-year periods preceding the survey (1-60, 61-120, 121-180 and 181-240 months before the interview date) or four-year periods (1-48, 49-96, 97-144, 145-192, and 193-240 months before the interview date).
See Handling of Missing Values for Age-Specific Fertility Rates (ASFR).
Since the time periods are five years or less in duration, the calculation of women-years of exposure is the same as that for current age-specific fertility rates with the total duration within each period per woman of 60 (or 48) months for five-year (or four-year) periods, respectively.
For five-year time periods, the following ASFRs will be truncated:
Period |
Age Group |
|
0-4 years |
45-49 |
|
5-9 |
40-44 |
|
10-14 |
35-39 |
|
15-19 |
30-34 |
For four-year time periods, the following ASFRs will be truncated:
Period |
Age Group |
|
0-3 years |
45-49 |
|
4-7 |
40-44, 45-49 |
|
8-11 |
35-39, 40-44 |
|
12-15 |
35-39 |
|
16-19 |
30-34, 35-39 |
The four-year period is used where birth displacement at five years of age is thought to be important.
DHS-8 Tabulation plan: Table 5.3.1 and 5.3.2
API Indicator IDs:
FE_FRTT_W_A15, FE_FRTT_W_A20, FE_FRTT_W_A25, FE_FRTT_W_A30, FE_FRTT_W_A35, FE_FRTT_W_A40, FE_FRTT_W_A45
The total fertility rate (TFR) is an age-period fertility rate for a synthetic cohort of women. It measures the average number of births a group of women would have by the time they reach age 50 if they were to give birth at the current age-specific fertility rates. The TFR is expressed as the average number of births per woman. Unless otherwise specified, the TFR is for all women.
Coverage:
Population base: Women age 15-49 (IR file)
Time period: Three years preceding the survey, excluding the month of interview (1-36 months before the survey)
The TFR is the sum of the Age-Specific Fertility Rate (ASFR) for all women multiplied by five. The ASFRs are those for the seven five-year age groups from 15-19 to 45-49.
See Handling of Missing Values for Age-Specific Fertility Rates (ASFR).
The TFR for women age 15-44 is sometimes presented in DHS reports as a variant. It uses the ASFRs from the 6 five-year age groups from 15-19 to 40-44.
The TFR is presented only for women age 15-49 and does not include the ASFR for girls age 10-14, which is generally negligible.
See References for Age-Specific Fertility Rates (ASFR).
DHS-8 Tabulation plan: Tables 5.1 and 5.2
API Indicator ID:
FE_FRTR_W_TFR
WHO 100 Core Health Indicators: Total fertility rate
The general fertility rate (GFR) is the average number of children currently being born to women of reproductive age in the period, typically 1-36 months preceding the survey, expressed per 1,000 women age 15-44
Coverage:
Population base: Women age 15-44 during the time period (IR file)
Time period: Three years preceding the survey excluding the month of interview (1-36 months)
Numerator: Total number of births in the period (v008 - b3 in 1:36) (BR file)
Denominator: Total number of women-years of exposure during period (IR file)
Variables: BR file, IR file.
|
b3 |
CMC date of birth of child |
|
v011 |
CMC date of birth of respondent |
|
v008 |
CMC date of interview |
|
v005 |
Woman’s individual sample weight |
|
awfactt |
All women factor (only needed with ever-married samples) |
Numerator: The total of all births in the period to all women age 15-49, irrespective of their age at the time of birth (v008 - b3 in 1:36).
Denominator: The sum of the women-years of exposure over the five-year age groups from 15-19 to 40-44 tabulated as for the age-specific fertility rates.
GFR is the numerator divided by the denominator, multiplied by 1000.
See Handling of Missing Values for Age-Specific Fertility Rates (ASFR).
All births in the period are counted including births to women age 45-49 and births to women before they reached age 15. The exposure is limited to women age 15-44 and does not count the exposure for women age 45-49 in the denominator. In the literature the denominator for the general fertility rate is women of reproductive age and this is sometimes based on women age 15-44 and other times women age 15-49. The DHS Program uses a denominator based on women age 15-44 as was used in the World Fertility Survey.
For ever-married samples, all women factors are applied in the tabulation of the denominators, as for the age-specific fertility rates.
See References for Age-Specific Fertility Rates (ASFR).
DHS-8 Tabulation plan: Table 5.1
API Indicator ID:
FE_FRTR_W_GFR
The crude birth rate (CBR) is the annual average number of births per thousand of the whole population
Coverage:
Population base: All women age 15-49 (IR file)
Time period: Three years preceding the survey, excluding the month of interview (1-36 months)
Numerator: Total number of births in the three years preceding the survey (v008 - b3 in 1:36) (BR file)
Denominator: Total number of person-years of exposure during the three years preceding the survey (PR file)
Variables: PR file.
|
hv103 |
Stayed in the household the previous night (de facto) |
|
hv104 |
Sex of household member |
|
hv105 |
Age of household member |
|
hv005 |
Household sample weight |
The crude birth rate is calculated by summing the product of the current age-specific fertility rates and the proportion of women in the specific age group out of the total de facto population based on the household members (PR) file:
See Age-Specific Fertility Rate (ASFR) for the calculation of the ASFRs.
For the proportion of women in the specific age group out of the total de facto population:
Numerator: From the household members (PR) file, the number of women who slept in the household the night before the interview tabulated by five-year age group (according to age reported in the household schedule) for groups 15-19 to 45-49.
Denominator: From the household survey, the total number of people of both sexes and all ages who slept in the household the night before the interview.
Sex of household member is always assigned. It may be possible that in early DHS surveys sex had missing values. In that case the household member was included in the denominator, but not the numerator.
Women with unknown age are assumed to be outside the 15-49 year range; thus they are not tabulated for numerators. People of either sex with unknown age are included in the denominators.
Nominally the calculation of the crude birth rate is just the number of births in the period based on the BR file divided by the total de facto population based on the PR file, however, because there is some level of non-response to the women’s questionnaire the number of births would be an underestimate relative to the population, and thus would bias downwards the crude birth rate. To avoid this problem, the calculation instead takes each of the age-specific fertility rates (ASFRs) for women age 15-19 to age 45-49, each of which has women as the denominator, and multiplies each of the ASFRs by the proportion of women in the age group compared to the total de facto population, and sums these products, as follows:
where i is the age group from 15-19 to 45-49, Womeniw is the number of women-years of exposure in age group i from the women’s questionnaire data (IR file), and Womenih is the count of women in age group i from the household population (PR file).
Assumptions: Due to the lack of birth dates for the household population, the proportion of women in each age group at the time of the survey is assumed to be the same as the proportion at the midpoint of the time period.
See References for Age-Specific Fertility Rates (ASFR).
DHS-8 Tabulation plan: Table 5.1
API Indicator ID:
FE_FRTR_W_CBR
Percentage of women age 15-49 years who report themselves as pregnant at the time of interview expressed as a percentage.
Coverage:
Population base: Women age 15-49 years (IR file)
Time period: Current status at time of survey
Numerator: Number of women age 15-49 who report themselves pregnant at the time of interview (v213 = 1)
Denominator: Number of women age 15-49
Variables: IR file.
|
v213 |
Currently pregnant |
|
v005 |
Woman’s individual sample weight |
|
awfactt |
All women factor (only needed with ever-married samples) |
Numerator divided by denominator, multiplied by 100. In ever-married samples, the denominator is adjusted by the all women factor.
Women with missing and “don’t know” responses are considered not pregnant. Women who do not know or are unsure whether they are pregnant or women with missing data on whether pregnant are excluded from the numerator but are included in the denominator.
The percentage of women currently pregnant is underreported because women who are in their early stage of pregnancy may not yet know if they are pregnant and because some women may not want to declare that they are pregnant. In ever-married samples, never-married women are assumed not to be pregnant.
DHS-8 Tabulation plan: Table 5.2
API Indicator ID:
FE_FRTY_W_PRG