Japan's Princess Kiko has given birth to a baby boy, potentially resolving the royal family's succession crisis.
Japanese welcomed news of the royal birth
The 39-year-old princess gave birth by a Caesarean section two weeks early, after complications in the pregnancy.
Princess Kiko, wife of the current emperor's second son, already has two daughters, but women are not allowed to ascend to the Chrysanthemum throne.
Her son becomes the first male heir to be born into Japan's royal family in more than four decades.
The present heir, Crown Prince Naruhito, and his wife, Princess Masako, have a young daughter, while Princess Sayako is married to a commoner, so if she were to have children they could not be considered.
Princess Kiko's son was born weighing 2,558 grams (5lbs 10oz) at 0827 local time (2327 GMT Tuesday).
Currently only males can ascend the Japanese throne
Emperor Akihito has two sons, Naruhito and Akishino
If Naruhito died without a male heir, Akishino succeeds
His baby son, so far unnamed, becomes third in line
Princess Sayako married a commoner so her children cannot ascend throne
Reports say mother and child are both in good condition.
The pregnancy has attracted enormous interest in Japan.
Princess Kiko has been in hospital since 16 August because of symptoms of partial placenta previa, a condition in which part of the placenta drops too low in the uterus.
Doctors said when she went into hospital that the move was precautionary and the pregnancy was proceeding well.
"I am very glad that the prince was born," said Chief Cabinet Secretary Shinzo Abe, who is likely to become Japan's next prime minister.
"I truly feel relieved and happy to receive a report that both the princess and the prince are fine.
"It's a refreshing feeling that reminds us of a clear autumn sky."
Princess Kiko and Prince Akishino already have two daughters
Conservatives had hoped Princess Kiko would give birth to a boy, thereby bringing an end to debate on whether the constitution should be revised to allow women to ascend to the throne.
Prime Minister Junichiro Koizumi had been advocating such a reform, and there appeared to be support for it amongst the Japanese public.
But the reform plans were shelved, amid strong opposition from conservative palace officials and some politicians, when the royal pregnancy was announced.
"Reforming the Imperial Household Law is an important issue that concerns the stability of the imperial family," said Shinzo Abe.
"We must carry on the debate in a careful and calm manner."
Japan's birth rate has continued to decline in recent years and the government has been working on ways of persuading women to have more children.
Baby and maternity product companies are also hoping the birth will benefit them.
Shares in baby-linked firms rose ahead of the birth, with one baby food company's shares hitting a high for the year on Monday, the Associated Press news agency reported.