The number of women in the age group considered fertile has decreased by 820,000 over the past 10 years, with the trend significantly impacting overall birthrate, a report by the National Assembly Research Service showed Wednesday.

The number of newborns in Korea began to drop significantly from the late 1990s and the birthrate is expected to continue dropping as women born in this timeframe reach fertile age.

Fertile women refer to those aged between 15 and 49. The report said that this age group has consistently declined in the past decade.

This also explains the current trend in which despite the rise in fertility rate -- the average number of babies that a woman is projected to have during her lifetime -- the number of newborn babies continued to fall, the report said.