The information was published in the 2023 report on Population, Labor and Employment, which was released this week by the General Statistics Office of Vietnam (GSO).
In 2022, this ratio was 113.7 boys to 100 girls, and was considered "severe" by the General Office for Population and Family Planning.
In 2020, it was 112.1, and in 2019, 111.5 girls to 100 boys.
Previous reports have already pointed out that the gender imbalance negatively affects the future population structure and results in a surplus of males.
In 2020, the GSO predicted that Vietnam would have an excess of 1.5 million men aged 15 to 49 by 2034, and that figure would rise to 1.8 million by 2059 if the sex ratio at birth imbalance remains unaddressed.
It said the lack of women would result in early marriages for young girls, leading to school dropouts and an increase in women trafficking.
Vietnam's total fertility rate last year was 1.95 children per woman, a drop compared to last year's 2.01 ratio and a replacement ratio of 2.1.
The latest rate has halved compared to 3.8 children per woman in 1989, and the GSO said it could drop lower in the future.
Last year, Vietnam’s population reached 100.3 million, with a fairly balanced ratio of men to women as male accounted for 49.9% and female 50.1%.
The declining birth rate is slowing population growth, with 2023 seeing a rate of 0.84%, down from 0.98% the previous year.
The GSO said the "unprecedentedly rapid" aging population and declining birth rates were shifting Vietnam's demographic structure towards an increased proportion of elderly and a decrease in younger people.
The proportion of young people in Vietnam's population fell from 23% in 2020 to 20.9% late last year, putting the country at risk of a labor shortage.
In 2020, Vietnam had 22.6 million people aged 15-24 but the figure dropped to 20.7 million by the end of last year, the National Assembly's Committee for Culture and Education said in October.
This means the number of young workers dropped by 170,000 per year.