Tokyo ? Japan’s Princess Kiko gave birth to a boy early today, providing the centuries-old Chrysanthemum Throne with its first male heir in more than 40 years.

The birth came about an hour after Kiko, 39, was reported to have undergone a Caesarean section. The boy is the third in line to the throne, after Crown Prince Naruhito and Kiko’s husband, Prince Akishino.

The infant was born at 8:27 a.m. and weighed 5.64 pounds, the Imperial Household Agency said. It said that both mother and child were in good condition afterward.

The arrival of a royal boy forestalled a looming succession crisis for the royal family. Japan’s 1947 succession law allows only males to ascend the throne, and prior to today Naruhito and Akishino were the only royals eligible for the crown.

Kiko, who already had two daughters, was hospitalized on Aug. 16 after showing symptoms of partial placenta previa, in which part of the placenta drops too low in the uterus.

The gender of the baby had been a closely guarded palace secret, though Japanese tabloids speculated the child would be a boy.

The last potential male heir born was Akishino himself, in 1965. Emperor Akihito’s eldest son, Naruhito, has a daughter with his wife, Masako, but the couple have no sons, meaning there is no one to inherit the throne after him and his brother. Kiko, likewise, had no sons.

The looming succession crunch had prompted serious discussion of changing the law to allow a female to assume the throne. The proposal had the support of Prime Minister Junichiro Koizumi and a majority of the public.

Even before the 1947 law, reigning empresses were rare, usually serving as stand-ins until a suitable male could be installed. The last reigning empress was Gosakuramachi, who assumed the throne in 1763.