Japanese Prime Minister Junichiro Koizumi has indicated he may no longer speed a bill through parliament to allow female royal succession.
Mr Koizumi initially pledged to put the bill to parliament by June
Mr Koizumi's slower approach came one day after the news that Princess Kiko was pregnant, raising hopes a male heir may yet be born into the royal family.
"I want to proceed cautiously so as not to make this a political tool," Mr Koizumi said of the controversial bill.
The bill was first proposed because no male royal has been born for 40 years.
But the imperial agency announced on Tuesday that Princess Kiko, the wife of Emperor Akihito's second son Prince Akishino, was pregnant.
If she has a son, it could dramatically alter the current situation in the imperial family, where there has been increasing concern over who will succeed the throne after Crown Prince Naruhito.
Naruhito, first in line to the throne after his father Akihito, has just one daughter with his wife, Crown Princess Masako.
Princess Kiko and Prince Akishino currently have two daughters.
Moves to allow female succession have prompted fierce debate in Japan.
Currently only males can ascend the Japanese throne
Emperor Akihito has two sons, Naruhito and Akishino
If Naruhito died without a male heir, his brother, Akishino, succeeds
But he has no sons either
Their sister, Princess Sayako, married a commoner so her children cannot ascend throne
Many Japanese support the idea, but conservatives oppose any change to the country's male-only imperial law.
Mr Koizumi had earlier pledged to propose the bill to parliament by June.
Asked on Wednesday whether he was keeping to this timescale, Mr Koizumi reportedly avoided a clear-cut answer.
"The issue does not involve a question of whether I stick to [the timing] or not," Mr Koizumi said.
"It's desirable that the legislation be enacted when everyone can support it," Mr Koizumi told parliament.
"Now public opinion is split, and I would like to deal with the issue carefully."