"The fertility rate of Japanese women in 2004 remained at the record low of 1.29 children per woman, the same as the previous year, a survey showed."
That's a record low? Even if you could get pregnant immediately after giving birth, if the mother brought the baby to full term, that would be a fertility rate of 1.33. Are all Japanese women pregnant all the time?
The total fertility rate is the average number of children born to a woman over her entire lifetime, not each year. 2.1 is considered to be the replacement rate where population will be stable. Below this population falls without immigration to make up for the shortfall. Japan has little immigration.