The fertility rate of Japanese women in 2003 fell below 1.3 for the first time, a revelation that could have severe repercussions for the future of the nation’s ailing public pension scheme, according to preliminary health ministry statistics released Thursday.

The total fertility rate, or the average number of children a woman can have during her lifetime, showed a major drop to 1.29 from the 2002 rate of 1.32. This reflects a faster decline in the number of births than the government had anticipated, according to demographic statistics compiled by the Health, Labor and Welfare Ministry.

The ministry will release the final figures soon.

Experts fear that the accelerating pace of the birthrate decline is bound to affect Japan’s social security system, including the pension program, given that the scheme’s design is based on government projections regarding the total fertility rate.

A recently enacted package of pension reform laws features a plan to gradually raise premiums for public pension programs while reducing benefits for pensioners. The government says the plan is aimed at protecting the pension program from collapsing under the weight of Japan’s aging population and falling birthrate.

The package calls for the government to ensure that future pension benefit levels do not fall below 50 percent of average take-home pay, and that pension premiums from fiscal 2017 are fixed at 18.3 percent of income.

But this scenario is based on the premise that the total fertility rate is 1.39.

Chief Cabinet Secretary Hiroyuki Hosoda downplayed the effect of the latest statistics on the future of the pension scheme, saying that the figure for last year stems from “certain special factors.”

He said he does not think that the figure “will continue to drop.” He dismissed suggestions that the government had withheld the statistics until after the pension laws were enacted.

According to ministry statistics, the total fertility rate has been steadily decreasing since the 1970s and now stands at the lowest level among major industrialized nations.