The decline in the number of births in Japan continues unabated. The chart below shows the rate of decline in the number of births in Japan over the past 10 years (2015-2025) by prefecture, based on the recently released preliminary figures. The decline is significant, with the highest rate being 48.1% in Akita Prefecture and the lowest rate being 20.7% in Tokyo.
Data source: Ministry of Health, Labour and Welfare Vital Statistics
In fact, if we look at the trend in birth numbers in Japan (preliminary figures), we see that the number of births is hitting new lows almost every year. Last year, 2025, was no exception, with the number of births hitting a new low of 705,809.
Although the number has decreased, it is still a good result
In fact, just around this time last year, we used time series analysis to predict the number of births in 2025 based on data on the number of births up to 2024 .
To reprint the article from that time, we predicted that the number of births in 2025 would be 686,798.
昨年同時期に投稿したブログの引用A quote from a blog post I made around the same time last year:
In fact, in news reports,Before the birth figures for 2025 were announced, they were predicted to be around 660,000 to 670,000. Compared to these predictions, the actual number of births wasThe number just barely exceeded 700,000, so it can be said to be a good result given the downward trend .
Considering Japan's future, it would be desirable for the results to exceed the forecast.
Birth rate forecast for 2026
Now, let's predict the number of births this year (2026). For the analysis, we will use monthly data from January 2015 to December 2025.
Last year, we made a prediction using data on the number of births across Japan, but this time we will predict the number of births by prefecture and add them up to predict the number of births across Japan in 2026.
Therefore, we will use data such as the following, which enters the number of births by year and month for each prefecture.
The analysis will be carried out using the JMP platform [Time Series Forecasting] .
The feature of this time series forecasting is that it automatically applies multiple smoothing models and then automatically selects the most appropriate model to make a forecast.In addition, even for data with many series, such as by prefecture, as in this case, it is possible to apply the optimal model for each series.
For the above data, select [Analysis] > [Advanced Modeling] > [Time Series Forecasting] , and specify "Number of Births" for [Y], "Year/Month" for [Time], and "Prefecture" for [Grouping Variable]. This will display the "Modeling Settings" report, allowing you to configure detailed settings for forecasting.
By default, the 19 models checked in the "Model Selection" report will be applied. In addition, in "Forecast Settings," you can set the forecast period as the NAhead value. Since this data is monthly and the NAhead value is 12, the forecast will cover the number of births from January to December 2026 .
Prediction results
This is a report of when a model was fitted to each prefecture. "Model Type" displays the type of best model that was fitted, and "Model Report" displays a graph of the original series (the series used for prediction) and the predicted series that were fitted with that model.
The figure below shows the forecast for Hokkaido, which is predicted to decline further by 2026.
You can switch prefectures by clicking "Select time series" in the upper left corner of the report. By switching between prefectures and checking the forecasts for each prefecture, you can see that birth rates are predicted to decrease in most prefectures in 2026.
However, this is not the case when we look at the forecast for Tokyo. Looking at the forecast graph, it is predicted that the number of cases will remain flat or even increase.
By selecting "Save Results" from the red triangle button in the "Time Series Forecast" report, you can save the original and forecast series values for each prefecture in a data table.
Using the saved data table, I graphed the predicted number of births in Japan in 2026. In the bar graph below, the blue bars are the actual values, and the orange bars (2026) are the predicted values.
Looking at Japan as a whole, the number of births has been decreasing year by year, and it is predicted that the number will decrease again this year.
The same can be said when looking at each prefecture, with Tokyo being the only one predicted to see an increase of around 1,300 people.
Tokyo and Ishikawa Prefecture are the only prefectures where the number of births is expected to increase from the previous year in 2025. Unfortunately, however, Ishikawa Prefecture is predicted to see a decrease.
Is there anything that can stop the decline in the birth rate?
The above discussion is based solely on the number of births predicted for this year using past birth figures. Of course, births are likely to be influenced by various factors, such as government policies and the economic environment.
The only bright spot is that the number of marriages is on the rise in 2024 and 2025. The number of marriages in 2025 is expected to increase by 5,657 compared to the previous year.
I don't know if it will be as simple as an increase in the number of marriages leading to an increase in the number of births, but I think it could be a factor in halting population decline, even if only a little.
The Japanese government is also making serious efforts to address the declining birthrate, so we will be keeping a close eye on future developments.
by Naohiro Masukawa (JMP Japan)
Naohiro Masukawa - JMP User Community
