The princess and her unborn baby are in good condition, with the latter moving inside the womb, Ichiro Kanazawa, medical supervisor of the Imperial Household, told a press conference.
''That is very auspicious. I would like her to give birth to a healthy baby,'' Prime Minister Junichiro Koizumi told reporters after learning of the delivery schedule.
If a boy is born, he will be the much-awaited first heir born to the Japanese imperial family in nearly 41 years and the drive toward revising the law to stipulate a new imperial succession order is expected to lose momentum.
But if a girl is born, the dearth of heirs in the family is likely to reignite the debate over whether to revise the Imperial House Law to let an emperor's first child ascend the throne.
The 1947 law limits imperial successors to males who have emperors on their fathers' side. The 4-year-old Princess Aiko, the only child of Crown Prince Naruhito and his wife Crown Princess Masako, cannot assume the throne after her father under the current law.
A baby boy will stand third in line to the Chrysanthemum Throne after the emperor's elder son Crown Prince Naruhito, 46, and the baby's father Prince Akishino, 40. With the looming succession crisis apparently receding, the legislative drive toward changing the law, which had come to a halt due to Princess Kiko's pregnancy, would stagnate further.
A baby girl will be the royal couple's third daughter. Boy or girl, the baby will be the fourth grandchild of the emperor, 72, and his wife Empress Michiko, 71, and the 23rd member of the imperial family alive today.
The 39-year-old Princess Kiko awaits her operation at Aiiku Hospital in Tokyo's Minato Ward, where she has stayed since Aug. 16 to prepare for a Caesarean delivery. She has a complication called partial placenta previa and faces a risk of massive bleeding that could occur toward the end of her pregnancy.
The complication is caused when the placenta forms low in the uterus and partially covers the cervix.
The Caesarean operation will be the first for the imperial family and for the princess, who had given birth to her two daughters, Princess Mako, 14, and Princess Kako, 11, by natural delivery.
Masao Nakabayashi, the princess' chief physician who heads the hospital, will perform the operation. The princess has also had some of her blood taken in the event that she requires a transfusion during the operation, the agency said.
Wednesday falls in the 37th week of the princess's pregnancy and was chosen as the delivery date after taking into account the condition of her placenta and the fetus, the agency said.
Emperor Akihito and Empress Michiko will be away from Tokyo when their daughter-in-law gives birth on Wednesday because they will be visiting Hokkaido from Tuesday through Saturday.
The royal couple have told the princess and others not to worry about them being absent when she gives birth, according to the agency.
Princess Kiko had previously given birth at the Imperial Household Hospital on the grounds of the Imperial Palace in Tokyo, but Aiiku Hospital has been chosen this time, partly because it can handle emergency deliveries.
The last child born to the imperial family was Princess Aiko in 2001. All of the imperial family's nine children born after Prince Akishino in 1965 have been women.
Last November, a panel of experts appointed by Koizumi recommended changing the imperial succession law to allow female monarchs and their descendants to reign -- a move that would pave the way for Princess Aiko to succeed the throne after her father.
Eager to avert a succession crisis and backed by public opinion, the government planned to submit a bill to parliament earlier this year to revise the law in line with the panel's recommendation. But Princess Kiko's pregnancy postponed the move as soon as the news emerged on Feb. 7.
Koizumi's plan was facing growing opposition from conservative academics and lawmakers, even from within his own Liberal Democratic Party, who argued that although Japan had eight reigning empresses in the past, a ''male-line'' succession has always been preserved.
Conservatives feared that if Princess Aiko married a commoner and their first child succeeded the throne after her, the imperial line would shift to a ''female-line,'' which they say has never occurred during the monarchy's long history.
Prince Akishino and Princess Kiko, who met with each other while attending Tokyo's Gakushuin University, married in June 1990. Princess Mako and Princess Kako were born in 1991 and 1994.
Kyodo News
I hope its a girl
fu-k its another girl' I'd love to see the look on his face.
