Asia · South-Eastern Asia
Vietnam Demographics
Vietnam has passed 101 million residents, with below-replacement fertility, a large working-age share, and a rising older population.
Primary resident-count values use the 2024 Intercensal Population and Housing Survey. Comparable mid-year history, projections, migration, density and world-rank values use UN DESA World Population Prospects 2024 tabulations and World Bank WDI where noted.
Last updated: June 30, 2026
Core Demographic Indicators
Detailed Demographic Indicators
| Indicator | Value | Year | Source |
|---|---|---|---|
| Resident population | 101,112,656 | 2024 | 2024 Intercensal Population and Housing Survey |
| Male population | 50,346,030 | 2024 | 2024 Intercensal Population and Housing Survey |
| Female population | 50,766,626 | 2024 | 2024 Intercensal Population and Housing Survey |
| Sex ratio | 99.2 males per 100 females | 2024 | 2024 Intercensal Population and Housing Survey |
| Urban population | 38,599,637 | 2024 | 2024 Intercensal Population and Housing Survey |
| Urban population share | 38.2% | 2024 | 2024 Intercensal Population and Housing Survey |
| Rural population | 62,513,019 | 2024 | 2024 Intercensal Population and Housing Survey |
| Population density | 305 people per km2 | 2024 | 2024 Intercensal Population and Housing Survey |
| Population aged 0-14 | 23.3% | 2024 | 2024 Intercensal Population and Housing Survey |
| Population aged 15-64 | 67.4% | 2024 | 2024 Intercensal Population and Housing Survey |
| Population aged 65+ | 9.3% | 2024 | 2024 Intercensal Population and Housing Survey |
| Population aged 60+ | 14.2 million | 2024 | 2024 Intercensal Population and Housing Survey |
| Aging index | 60.2% | 2024 | 2024 Intercensal Population and Housing Survey |
| Total fertility rate | 1.91 children per woman | 2024 | 2024 Intercensal Population and Housing Survey |
| Urban fertility rate | 1.67 children per woman | 2024 | 2024 Intercensal Population and Housing Survey |
| Rural fertility rate | 2.08 children per woman | 2024 | 2024 Intercensal Population and Housing Survey |
| Crude birth rate | 13.5 live births per 1,000 people | 2024 | 2024 Intercensal Population and Housing Survey |
| Sex ratio at birth | 111.4 boys per 100 girls | 2024 | 2024 Intercensal Population and Housing Survey |
| Median age | 32.9 years | 2024 | UN WPP 2024 mid-year tabulation |
| Life expectancy at birth, total | 74.7 years | 2024 | UN WPP 2024 tabulation |
| Life expectancy at birth, male | 70.1 years | 2024 | UN WPP 2024 tabulation |
| Life expectancy at birth, female | 79.4 years | 2024 | UN WPP 2024 tabulation |
| Net migration | -59,645 | 2024 | UN WPP 2024 mid-year tabulation |
| World population share | 1.24% | 2024 | UN WPP 2024 mid-year tabulation |
| Global population rank | 16 | 2024 | UN WPP 2024 mid-year tabulation |
| Infant mortality rate | 14.7 deaths per 1,000 live births | 2024 | UN WPP 2024 tabulation |
| Under-5 mortality rate | 19.7 deaths per 1,000 live births | 2024 | UN WPP 2024 tabulation |
| Households | 28,146,939 | 2024 | 2024 Intercensal Population and Housing Survey |
Table analysis
- The 2024 survey count is 101,112,656 residents at the April 1 survey reference time.
- The official male-female split is close to even: 49.8% male and 50.2% female.
- The 15-64 group accounts for 67.4% of the population, while the 65+ group accounts for 9.3%.
- The 2024 fertility rate is 1.91 children per woman, below the 2.1 replacement-level benchmark.
- Official resident counts and UN mid-year estimates use different reference dates, so small differences between population rows are expected.
Population Trend
Vietnam Population Trend, 1955-2026
Mid-year population estimates and latest UN medium-variant estimate
Source: UN DESA World Population Prospects 2024 tabulation. Values are mid-year estimates and should not be merged with the April 1 resident-count survey value.
Trend analysis
- The UN mid-year series rises from 28.2 million in 1955 to 101.0 million in 2024.
- Growth is slower in recent rows: the 2024 table change is 0.63%, compared with 2.92% in 1960.
- The chart separates historical estimates from projections; future values appear in a separate projection section.
Detailed Population History
| Year | Population | Yearly % change | Yearly change | Net migration | Median age | Fertility rate | Density | Urban pop % | Urban population | World share | World population | Global rank | Source |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | 102,177,431 | 0.57% | 578,904 | -51,045 | 33.9 | 1.86 | 330 | 42.2% | 43,096,860 | 1.23% | 8,300,678,395 | 16 | UN WPP 2024 tabulation |
| 2025 | 101,598,527 | 0.60% | 610,841 | -48,171 | 33.4 | 1.88 | 328 | 41.4% | 42,039,428 | 1.23% | 8,231,613,070 | 16 | UN WPP 2024 tabulation |
| 2024 | 100,987,686 | 0.63% | 635,494 | -59,645 | 32.9 | 1.90 | 326 | 40.6% | 40,975,863 | 1.24% | 8,161,972,572 | 16 | UN WPP 2024 tabulation |
| 2023 | 100,352,192 | 0.67% | 671,537 | -81,789 | 32.4 | 1.91 | 324 | 39.8% | 39,908,501 | 1.24% | 8,091,734,930 | 16 | UN WPP 2024 tabulation |
| 2022 | 99,680,655 | 0.81% | 800,732 | -78,977 | 31.9 | 1.93 | 321 | 39.0% | 38,841,525 | 1.24% | 8,021,407,192 | 16 | UN WPP 2024 tabulation |
| 2020 | 98,079,191 | 1.11% | 1,051,187 | -6,457 | 31.0 | 1.96 | 316 | 37.4% | 36,727,248 | 1.24% | 7,887,001,292 | 15 | UN WPP 2024 tabulation |
| 2015 | 92,823,254 | 1.20% | 1,073,620 | -4,888 | 29.2 | 2.10 | 299 | 34.1% | 31,635,369 | 1.24% | 7,470,491,872 | 15 | UN WPP 2024 tabulation |
| 2010 | 87,455,152 | 1.52% | 1,273,368 | -4,443 | 27.2 | 1.91 | 282 | 30.8% | 26,910,696 | 1.25% | 7,021,732,148 | 15 | UN WPP 2024 tabulation |
| 2005 | 81,088,313 | 1.00% | 786,860 | -208,337 | 24.8 | 1.89 | 262 | 28.4% | 23,000,555 | 1.23% | 6,586,970,132 | 15 | UN WPP 2024 tabulation |
| 2000 | 77,154,011 | 1.38% | 1,020,814 | -144,298 | 22.7 | 2.03 | 249 | 25.4% | 19,568,590 | 1.25% | 6,171,702,993 | 14 | UN WPP 2024 tabulation |
| 1995 | 72,049,940 | 1.92% | 1,309,078 | -51,147 | 20.6 | 2.70 | 232 | 23.1% | 16,668,571 | 1.25% | 5,758,878,982 | 13 | UN WPP 2024 tabulation |
| 1990 | 65,504,552 | 2.09% | 1,288,786 | -57,221 | 19.5 | 3.60 | 211 | 21.1% | 13,817,423 | 1.23% | 5,327,803,110 | 13 | UN WPP 2024 tabulation |
| 1985 | 59,060,622 | 2.39% | 1,314,104 | -124,910 | 18.9 | 4.21 | 190 | 20.2% | 11,942,117 | 1.21% | 4,868,943,465 | 13 | UN WPP 2024 tabulation |
| 1980 | 52,490,101 | 2.46% | 1,201,440 | -74,791 | 18.4 | 4.79 | 169 | 19.9% | 10,464,982 | 1.18% | 4,447,606,236 | 16 | UN WPP 2024 tabulation |
| 1975 | 46,482,903 | 2.31% | 1,001,535 | -2,010 | 17.6 | 5.62 | 150 | 19.7% | 9,152,476 | 1.14% | 4,070,735,277 | 17 | UN WPP 2024 tabulation |
| 1970 | 41,475,230 | 2.24% | 869,115 | 1,997 | 17.2 | 6.02 | 134 | 19.2% | 7,943,534 | 1.12% | 3,694,683,794 | 17 | UN WPP 2024 tabulation |
| 1965 | 37,129,656 | 2.68% | 919,545 | -1,438 | 17.7 | 6.16 | 120 | 16.7% | 6,216,854 | 1.11% | 3,334,533,703 | 17 | UN WPP 2024 tabulation |
| 1960 | 32,531,933 | 2.92% | 873,097 | 0 | 20.2 | 6.27 | 105 | 14.8% | 4,802,582 | 1.08% | 3,015,470,894 | 17 | UN WPP 2024 tabulation |
| 1955 | 28,166,446 | 2.33% | 613,142 | 0 | 22.0 | 5.54 | 91 | 13.1% | 3,685,807 | 1.03% | 2,740,213,792 | 18 | UN WPP 2024 tabulation |
Table analysis
- The table uses one mid-year source family, which keeps population, migration, density, urban share and world-share fields on the same definition.
- Vietnam moved from rank 18 in 1955 to rank 16 in the 2024 mid-year table.
- Urban share rises from 13.1% in 1955 to 40.6% in 2024 in the UN-based tabulation.
- Fertility falls from 6.27 children per woman in 1960 to 1.90 in 2024 in this same table.
- The official 2024 survey count is higher than the 2024 mid-year table because the datasets use different reference dates and compilation methods.
Age Structure
Vietnam Broad Age Structure
Share of population by broad age group in the 2024 survey
Source: 2024 Intercensal Population and Housing Survey. Counts in the table are derived from the published total and rounded age-share percentages.
| Age group | Population | Share | Year | Source |
|---|---|---|---|---|
| 0-14 | Approx. 23,559,249 | 23.3% | 2024 | 2024 Intercensal Population and Housing Survey |
| 15-64 | Approx. 68,149,930 | 67.4% | 2024 | 2024 Intercensal Population and Housing Survey |
| 65+ | Approx. 9,403,477 | 9.3% | 2024 | 2024 Intercensal Population and Housing Survey |
Data analysis
- The working-age group is the largest broad group at 67.4%.
- The 65+ share is 9.3%, up from the 2019 census share of 7.7% reported in the 2019 age-sex table.
- The age-group population counts are derived from rounded shares, so they should be read as approximate counts.
Age-Sex Population Structure
Vietnam Population Pyramid
Population by five-year age group and sex, 2019 census
Source: 2019 Population and Housing Census table, as published by UN Statistics Division Demographic Yearbook materials. The 2024 survey summary provides broad age groups, not a full published five-year age-sex table in the source used here.
| Age group | Male | Female | Total | Male share | Female share | Sex ratio | Year | Source |
|---|---|---|---|---|---|---|---|---|
| 0-4 | 4,100,479 | 3,718,847 | 7,819,326 | 52.4% | 47.6% | 110.3 | 2019 | 2019 Census / UN Demographic Yearbook |
| 5-9 | 4,354,887 | 3,977,832 | 8,332,719 | 52.3% | 47.7% | 109.5 | 2019 | 2019 Census / UN Demographic Yearbook |
| 10-14 | 3,737,030 | 3,482,807 | 7,219,837 | 51.8% | 48.2% | 107.3 | 2019 | 2019 Census / UN Demographic Yearbook |
| 15-19 | 3,352,386 | 3,153,831 | 6,506,217 | 51.5% | 48.5% | 106.3 | 2019 | 2019 Census / UN Demographic Yearbook |
| 20-24 | 3,417,149 | 3,258,554 | 6,675,703 | 51.2% | 48.8% | 104.9 | 2019 | 2019 Census / UN Demographic Yearbook |
| 25-29 | 4,301,210 | 4,146,767 | 8,447,977 | 50.9% | 49.1% | 103.7 | 2019 | 2019 Census / UN Demographic Yearbook |
| 30-34 | 4,276,404 | 4,117,406 | 8,393,810 | 50.9% | 49.1% | 103.9 | 2019 | 2019 Census / UN Demographic Yearbook |
| 35-39 | 3,891,950 | 3,800,436 | 7,692,386 | 50.6% | 49.4% | 102.4 | 2019 | 2019 Census / UN Demographic Yearbook |
| 40-44 | 3,366,147 | 3,317,972 | 6,684,119 | 50.4% | 49.6% | 101.5 | 2019 | 2019 Census / UN Demographic Yearbook |
| 45-49 | 3,132,172 | 3,125,299 | 6,257,471 | 50.1% | 49.9% | 100.2 | 2019 | 2019 Census / UN Demographic Yearbook |
| 50-54 | 2,772,157 | 2,889,853 | 5,662,010 | 49.0% | 51.0% | 95.9 | 2019 | 2019 Census / UN Demographic Yearbook |
| 55-59 | 2,402,096 | 2,706,628 | 5,108,724 | 47.0% | 53.0% | 88.7 | 2019 | 2019 Census / UN Demographic Yearbook |
| 60-64 | 1,810,497 | 2,181,537 | 3,992,034 | 45.4% | 54.6% | 83.0 | 2019 | 2019 Census / UN Demographic Yearbook |
| 65-69 | 1,167,214 | 1,518,057 | 2,685,271 | 43.5% | 56.5% | 76.9 | 2019 | 2019 Census / UN Demographic Yearbook |
| 70-74 | 687,339 | 953,511 | 1,640,850 | 41.9% | 58.1% | 72.1 | 2019 | 2019 Census / UN Demographic Yearbook |
| 75-79 | 453,972 | 717,839 | 1,171,811 | 38.7% | 61.3% | 63.2 | 2019 | 2019 Census / UN Demographic Yearbook |
| 80-84 | 327,330 | 580,402 | 907,732 | 36.1% | 63.9% | 56.4 | 2019 | 2019 Census / UN Demographic Yearbook |
| 85+ | 330,642 | 680,345 | 1,010,987 | 32.7% | 67.3% | 48.6 | 2019 | 2019 Census / UN Demographic Yearbook |
Age-sex analysis
- The 2019 census age-sex table totals 96,208,984 people: 47,881,061 male and 48,327,923 female.
- Male shares are above 50% from age 0-4 through 45-49.
- The sex ratio falls below 100 in age group 50-54, where the table shows 95.9 males per 100 females.
- Older ages are female-heavy: age 85+ has 330,642 males and 680,345 females.
- The 2019 five-year age-sex table is not interchangeable with 2024 broad age shares; the source year and age grouping differ.
Sex Ratio by Age Group
Males per 100 females by age group, 2019 census
Source: 2019 Population and Housing Census table, as published through UN Demographic Yearbook materials. Sex ratio is calculated as males per 100 females from the table counts.
Chart analysis
- The highest age-group sex ratio in the 2019 table is 110.3 in age group 0-4.
- The age group nearest parity is 45-49, at 100.2 males per 100 females.
- The lowest value is 48.6 in age group 85+.
Fertility, Life Expectancy and Urbanization
Fertility Compared With Replacement Level
Total fertility rate in 2024 compared with a 2.1 benchmark
Source: 2024 Intercensal Population and Housing Survey. Replacement level is a broad benchmark, not a country-specific threshold.
Chart analysis
- Vietnam’s 2024 fertility rate is 1.91 births per woman.
- The rate is 0.19 births per woman below the broad 2.1 replacement-level benchmark.
- The same survey reports an urban-rural fertility split of 1.67 in urban areas and 2.08 in rural areas.
Life Expectancy by Sex
Life expectancy at birth in years, 2024 UN WPP tabulation
Source: UN DESA World Population Prospects 2024 tabulation.
Chart analysis
- Female life expectancy is 79.4 years and male life expectancy is 70.1 years.
- The female-male gap in this 2024 tabulation is 9.3 years.
- The total value is 74.7 years because it combines both sexes under the source’s period life-table method.
Urban Population Share
Urban and rural population split in the 2024 survey
Source: 2024 Intercensal Population and Housing Survey. Urban classification follows the national statistical definition used in the survey.
Data analysis
- The 2024 survey reports 38.6 million urban residents and 62.5 million rural residents.
- Urban residents account for 38.2% of the resident population in the survey.
- The UN mid-year table reports a different 2024 urban count because its population definition and reference date differ.
Population Projection
Vietnam Population Projection, 2030-2050
UN medium-variant projection years
Source: UN DESA World Population Prospects 2024 medium-fertility variant tabulation. Population projections are scenario-based estimates, not guaranteed predictions.
| Year | Projected population | Yearly % change | Yearly change | Net migration assumption | Median age | Fertility rate | Density | Urban pop % | Urban population | Scenario | Source |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2030 | 104,254,902 | 0.52% | 531,275 | -25,752 | 35.7 | 1.82 | 336 | 45.3% | 47,248,046 | Medium-fertility variant | UN WPP 2024 tabulation |
| 2035 | 106,530,676 | 0.43% | 455,155 | -29,899 | 37.4 | 1.78 | 344 | 49.0% | 52,215,812 | Medium-fertility variant | UN WPP 2024 tabulation |
| 2040 | 108,437,635 | 0.36% | 381,392 | -36,057 | 38.2 | 1.77 | 350 | 52.5% | 56,944,758 | Medium-fertility variant | UN WPP 2024 tabulation |
| 2045 | 109,685,398 | 0.23% | 249,553 | -27,395 | 39.0 | 1.76 | 354 | 56.0% | 61,416,054 | Medium-fertility variant | UN WPP 2024 tabulation |
| 2050 | 110,008,908 | 0.06% | 64,702 | -32,395 | 40.2 | 1.75 | 355 | 59.7% | 65,711,413 | Medium-fertility variant | UN WPP 2024 tabulation |
Projection analysis
- The medium-variant table reaches 110,008,908 people in 2050.
- The projected annual change narrows from 531,275 in 2030 to 64,702 in 2050.
- Projected median age rises from 35.7 in 2030 to 40.2 in 2050.
- Projected urban share rises from 45.3% in 2030 to 59.7% in 2050.
- Projection rows are scenario-based and should not be presented as observed population counts.
Urban Areas and Regional Distribution
| Area | Population | Share | Growth note | Year | Source |
|---|---|---|---|---|---|
| Ho Chi Minh City | 9,521,886 | Data not available | Largest locality by population | 2024 | 2024 Intercensal Population and Housing Survey |
| Hanoi | 8,685,607 | Data not available | Second-largest locality by population | 2024 | 2024 Intercensal Population and Housing Survey |
| Red River Delta | 24.0 million | 23.7% | Highest regional population total reported in the summary | 2024 | 2024 Intercensal Population and Housing Survey |
| Central Highlands | 6.2 million | 6.2% | Lowest regional population total reported in the summary | 2024 | 2024 Intercensal Population and Housing Survey |
| Southeast region | Data not available | Data not available | Highest 2019-2024 average annual regional growth: 1.46% | 2024 | 2024 Intercensal Population and Housing Survey |
| Mekong Delta | Data not available | Data not available | Lowest 2019-2024 average annual regional growth: 0.29% | 2024 | 2024 Intercensal Population and Housing Survey |
Table analysis
- Ho Chi Minh City is the largest named locality in the 2024 summary, with 9,521,886 people.
- Hanoi follows with 8,685,607 people.
- The Red River Delta is reported at 24.0 million people, or 23.7% of the national population.
- Some regional totals are not in the summary source used here; those cells are marked as Data not available rather than filled from another definition.
Country Comparison
The comparison uses countries commonly discussed alongside Vietnam because of Southeast Asian population scale and demographic transition. Values use World Bank WDI where the same indicator and year are available.
| Country | Population | Population growth | Life expectancy | Net migration | Source note |
|---|---|---|---|---|---|
| Vietnam | 100,987,686 | 0.6% | 75 years | -48,171 | World Bank WDI: population, growth and life expectancy 2024; net migration 2025 |
| Thailand | 71,668,011 | -0.0% | 77 years | 27,509 | World Bank WDI: population, growth and life expectancy 2024; net migration 2025 |
| Philippines | 115,843,670 | 0.8% | 70 years | -149,315 | World Bank WDI: population, growth and life expectancy 2024; net migration 2025 |
Comparison analysis
- Vietnam’s 2024 WDI population is between Thailand and the Philippines in this three-country comparison.
- Vietnam’s 2024 WDI life expectancy is 75 years, below Thailand’s 77 and above the Philippines’ 70.
- World Bank net migration rows use 2025, while population, growth and life expectancy use 2024; the table labels this year difference directly.
Demographic Overview
The official 2024 resident count is 101.1 million, while the UN mid-year series shows continued growth through the 2020s at a slower pace than in earlier decades.
The 2024 survey places 67.4% of residents in ages 15-64, with 9.3% aged 65 and over.
The 2019 census table shows male-heavy younger groups and female-heavy older groups, with the sex ratio falling sharply after age 65.
The 2024 total fertility rate is 1.91 children per woman, with lower fertility in urban areas than in rural areas.
The 2024 survey records 38.6 million urban residents, equal to 38.2% of the official resident population.
The UN medium-variant table rises to about 110.0 million by 2050, with much slower annual growth by that point.
Data Sources and Methodology
| Source | Year or release | Used for |
|---|---|---|
| 2024 Intercensal Population and Housing Survey, National Statistics Office / MPI release | Reference date: April 1, 2024; release summary: 2025 | Official resident population, sex split, urban/rural split, density, broad age structure, fertility, crude birth rate, sex ratio at birth, households, selected localities and regional notes |
| UN DESA World Population Prospects 2024, tabulated through Worldometer-style mid-year tables | 2024 Revision; historical estimates 1955-2026 and medium-variant projections 2030-2050 used here | Historical mid-year population table, population trend chart, median age, net migration, fertility trend fields, density, urban share, world share, global rank, life expectancy, mortality indicators and projection table |
| 2019 Population and Housing Census / UN Statistics Division Demographic Yearbook table | Census reference date: April 1, 2019 | Detailed five-year age-sex table, population pyramid and sex ratio by age group |
| World Bank World Development Indicators | 2024 and 2025 latest values shown in the comparison table | Same-source comparison of Vietnam, Thailand and the Philippines for population, population growth, life expectancy and net migration |
Indicator Definitions
| Indicator | Definition | Unit | Source note |
|---|---|---|---|
| Resident population | Population counted by the national survey at the stated reference time. | People | The 2024 survey reference time is April 1, 2024. |
| Mid-year population | Population estimate for July 1 in a UN WPP year. | People | Used in historical and projection tables for comparability across countries. |
| Yearly change | Average or annual numerical change in the mid-year population table, depending on the source row. | People | UN-based tabulation; not calculated from the official April 1 survey total. |
| Net migration | Immigrants minus emigrants for the source period or year. | People | A negative number indicates more emigrants than immigrants in the source estimate. |
| Fertility rate | Total fertility rate, expressed as children per woman. | Births per woman | 2024 official survey value is used for the headline card and fertility chart. |
| Urban population share | Share of the population classified as urban under the source definition. | Percent | Urban definitions can differ between national statistics and UN urbanization series. |
| Sex ratio | Male population divided by female population, multiplied by 100. | Males per 100 females | Age-sex table ratios are calculated from 2019 census counts. |
| Projection | Scenario-based future population estimate. | People | UN medium-fertility variant is shown separately from historical estimates. |
Method note
- Official survey values and UN mid-year estimates are both useful, but they do not describe the same measurement point.
- Age-sex values use 2019 census counts because the available 2024 summary source gives broad age groups rather than a full five-year age-sex table.
- Rounded age-share values in the 2024 summary are used directly; derived counts are marked as approximate.
- Comparison values use World Bank WDI to keep country rows on the same source family.
Methodological Safety Note
Methodological Safety Note: Vietnam demographic values can vary by resident population, mid-year estimate, census count, model estimate and projection scenario. The 2024 official survey count is an April 1 resident-count measure, while UN WPP and World Bank tables use internationally comparable time series and mid-year estimates. Projection values are not observed counts. Urban population depends on the source definition. Sex ratios are males per 100 females. Age-sex rows use 2019 five-year census groups; 2024 broad age shares should not be treated as a full population pyramid. Missing values are not estimated unless the formula is stated.
FAQ
Why do Vietnam population totals differ between 2024 sources?
The 2024 Intercensal Population and Housing Survey reports a resident count at April 1, 2024. UN WPP and World Bank tables use comparable mid-year estimates, so the totals can differ.
Is the 2019 population pyramid current?
It is the latest detailed five-year age-sex table used on this page. The 2024 summary source supports broad age groups but not a full five-year age-sex table in the visible dataset used here.
Is Vietnam below replacement fertility?
Yes. The 2024 official total fertility rate is 1.91 children per woman, below the broad 2.1 replacement-level benchmark.
Are projection values guaranteed population counts?
No. Projection values are scenario-based estimates. The projection table uses the UN WPP 2024 medium-fertility variant and keeps those values separate from observed or estimated historical rows.