When Japan's Princess Kiko announced she was pregnant earlier this year, the government quickly shelved a much-debated proposal to avoid a succession crisis and allow a female to inherit the Chrysanthemum Throne.

Now Japan will find out when Kiko gives birth on Wednesday whether the throne will have its first male heir in four decades -- or if the nation will have to resume the highly emotional debate over the royal family's future.

The 39-year-old princess, wife of Prince Akishino, the emperor's second-eldest son, was scheduled to undergo Caesarean section on Wednesday morning in Tokyo. The couple has two daughters but no sons.

CountryWatch: Japan

The gender of the baby has been a closely guarded palace secret, though Japanese tabloids have speculated the child will be a boy, giving the country's male-only succession system a respite from a looming succession crunch.

"The imperial family has more than 1,000 and several hundred years of history," said Isao Tokoro, an imperial system expert at Kyoto Sangyo University. "If a boy is born ... it means a male emperor can assume the role of past emperors."

Japan's royals have a severe shortage of such candidates.

Neither Akishino nor his elder brother and first in line to the throne, Crown Prince Naruhito, have produced a boy. Naruhito and his Harvard-educated wife, Masako, have a 4-year-old daughter, Aiko.

Amid fears of succession troubles down the road, a high-profile panel last year recommended changing Japan's 1947 imperial law to allow a woman to take the throne. Currently, only men in a direct male line to the emperor can take the crown, so even the son of the emperor's daughter would not be eligible.

The revision proposal was extremely popular with the public, in part because of general adoration of Aiko and sympathy for her mother Masako, who came under intense court pressure to produce a male heir and has suffered in recent years from stress-induced depression.

Many also feel that it's time for Japan to change a law that some consider sexist.

"I'd rather it were a girl. I think the rule that only males can ascend the throne is a bit outdated," said Ichiko Nakagawa, 43, saleswoman on her way home in Tokyo on Tuesday evening. "The law should be revised whether it's a girl or a boy."

Highly vocal and well-connected conservatives, however, lobbied hard against law revision last year, despite Prime Minister Junichiro Koizumi's outspoken support for the reform.

Traditionalists argued that allowing women to carry the imperial line would destroy more than 1,000 years of Japanese culture, saying an emperor's Y-chromosome contained the essence of the royal family and should be preserved.

Instead of putting women on the throne, some opponents suggested reinstating the abolished prewar aristocracy to widen the pool of heirs. Others proposed bringing back the tradition of imperial concubines to breed potential emperors.

If Kiko has a boy, the child would be third in line to the throne after Naruhito and Akishino.

Conservatives were unabashed about their preference Tuesday.

"I am hoping for the birth of a boy," Justice Minister Seiken Sugiura stated to reporters Tuesday morning. "I am praying for a safe delivery."

The debate early this year became so fractious that support for revising the succession law began to wane among the conflict-averse public. When Kiko announced her pregnancy, raising the possibility that a boy could be born, Koizumi's government put the reform aside.

Many expected the birth of a boy on Wednesday to further quell talk about reform by forestalling a succession crisis for some years. The respite, however, would be temporary, since it would only be a matter of time before the family would have to produce more males.

The birth of a girl, however, was likely to renew the succession debate.

"If it's a girl, we'll need an immediate revision [of the law] or the imperial household will not be passed on," said Tokoro.

Still, it was uncertain whether Koizumi's presumed successor, conservative Shinzo Abe, would show the same enthusiasm for reform if he takes office later this month.

Some proponents of a change in the law, which could lead to the first woman on the throne since Gosakuramachi took the crown in 1763, say the debate should go ahead no matter what the gender of Kiko's baby.

"I think we will start discussing the issue again," said Eiko Shinotsuka, professor of gender studies at Ochanomizu University. "The proposal was something that was delivered by a bona fide conference that cannot be ignored."

CountryWatch: Japan